A pod such as the Litening III may be suitable.
“LITENING is a targeting pod integrated and mounted externally to the aircraft. The targeting pod contains a high-resolution, forward-looking infrared sensor (FLIR) that displays an infrared image of the target to the aircrew; it has a wide field of view search capability and a narrow field of view acquisition/targeting capability of battlefield-sized targets. The pod also contains a charged coupled device (CCD-TV) camera used to obtain target imagery in the visible portion of the electromagnetic spectrum. An on-gimbal inertial navigation sensor has established line-of-sight and automatic boresighting capability.
The pod is equipped with a laser designator for precise delivery of laser-guided munitions, a laser rangefinder provides information for various avionics systems, for example, navigation updates, weapon deliveries and target updates. The targeting pod includes an automatic target tracker to provide fully automatic stabilized target tracking at altitudes, airspeeds and slant ranges consistent with tactical weapon delivery maneuvers. These features simplify the functions of target detection and recognition, and permit attack of targets with precision-guided weapons on a single pass.
Length: 87 in (2.20 m)
Diameter: 16 in (0.406 m)
Weight: 440 lb (200 kg)
Cost $1.5M
http://en.wikipedia.org/wiki/LITENING_targeting_pod
Using this pod targets can be positively identified and the exact position of the target recorded, making it possible to hand-off the target to another platform.
This can be done in real time using such systems as ROVER. The there are many advantages to such systems, but the main one is that the people who call for the strike can confirm that the correct target has been identified before the weapon is released.
“ROVER, which stands for Remotely Operated Video Enhanced Receiver, is a system which allows ground forces, such as Forward Air Controllers (FAC), to see what an aircraft or unmanned aerial vehicle (UAV) is seeing in real time by receiving images acquired by the aircraft's sensors on a laptop on the ground. There's no time delay and usage of ROVER greatly improves the FAC on the ground reconnaissance and target identification which are essential to close air support.
ROVER IV seeks to use GPS and other systems to allow the controller to click a target they would like the aircraft to engage or the UAV operator to focus on. ROVER is compatible with UAVs and aircraft carrying the LITENING targeting pod as well as other targeting systems.”
http://en.wikipedia.org/wiki/ROVER
Some data on the PC-21.
http://www.pilatus-aircraft.com/media/Pilatus-PC-21.pdf
http://www.pilatus-aircraft.com/media/Pilatus-PC-21-Fact-Sheet.pdf
At 200kg the pod is rather heavy and I would expect that ideally it should be mounted on a centre station. However the undercarriage on this aircraft folds inwards and the gap between the semi-recessed wheels is only 0.6m/2ft. This is rather tight but I think its OK. The ground clearance is 0.82m/2.7ft, which would be reduced as the oleo legs compress, but this still should provide adequate clearance.
Obviously we are assuming that an armed version of the aircraft will be produced, with hard points etc. This should not be a problem as there are likely to customers for large numbers of armed versions of this aircraft.
In addition to the pod the aircraft would probably need external fuel tanks and be able to carry some light weapons.
Which brings me to the other turbo-prop transport aircraft. Mounting the weapons under the wings could be problematic as hard points will also be required. Extensive modifications would be required to install the hard points and the associated wiring. This would be a difficult task and would best be carried out during the original built rather than as a retrofit. Transport aircraft are designed to carry the load internally, rather than on the wings. So perhaps the weapons could be dropped from the rear ramp of a suitable aircraft, such as the C-27J Spartan.
Over the years many similar aircraft have been used to deliver loads by parachute. One technique is to put the load on a pallet attached to one (or more) large parachutes, the package sits on rollers and is extracted from the aircraft by a small drogue chute. A similar technique would work with bombs. Once clear from the aircraft the drogue chute would be released and the bomb would be guided to the designated target. This technique would not work with dumb bombs as the release would be too inaccurate, but it certainly would be good enough for smart bombs.
The USAF has used this technique for dropping very large bombs that could not be carried by fighters.
Another factor to consider is the cost of using smart weapons, they are very expensive, but few are required to take out a target. Also the value of the target has to be taken into account, there is little point in dropping a $1m weapon on $1,000 truck.
“Viper Strike is a gliding munition capable of stand-off precision attack using GPS-aided navigation and a semi-active laser seeker. It is intended for operations that require a flexible angle of inclination (steep or shallow), particularly in mountainous terrain or built-up areas where strict rules of engagement are in force. Its small size and precision provide for low collateral damage in cluttered urban environments.”
The weapon will be used on MQ-1 armed Predator and AC-130 gunships.”
http://www.defense-update.com/directory/viper-strike.htm
Length: 0.9 m
Weight: 20 kg
Diameter: 14 cm
Wingspan: 0.9 m
Warhead: 1.8 kg (HEAT)
http://en.wikipedia.org/wiki/Viper_Strike
Viper-Strike is a very small weapon. The installation on the AC-130U allows the weapon to be deployed in a canister through the floor of the aircraft in a similar manner to deploying sonar buoys on maritime aircraft. In this case the arrangement acts as an airlock and allows the aircraft to be pressurised, so that it can remain at high altitudes. This tactic allows the enemy to be engaged at considerable standoff ranges, offering good protection to the delivering aircraft and also providing considerable cross-track coverage.
Work is underway to reduce the weight and cost of the weapon. Other enhancements are being developed including modifications to the warhead and different warheads to enable the weapon to be used against a wide range of targets.
This weapon would also be suitable for use with the armed PC-21.
As mentioned elsewhere in this thread in COIN operations working in pairs has lots of advantages. Perhaps in this case two pairs might be better. In jungle or mountainous regions where it maybe difficult to spot targets from medium altitude, one pair could go down and identify targets, whilst the other pair operated at medium altitude and designated the targets handed off by the low pair. Singletons could be used but flying with a wingman is always better.
In this scenario (really a three layered approach), the weapons would be deployed from a turboprop transport aircraft operating at height (well high for a turboprop). It could carry a wide range of smart glide weapons (i.e. bombs of different sizes). Some versions of the C-130 even have under wing hard points and could carry large missiles or other equipment. These aircraft would have relatively long endurance and range when compared with the PC-21 aircraft. The transport aircraft could loiter in the area and service waves of PC-21s. With a mixed squadron of 4 transport aircraft (C-130 or C-27J) and 16 PC-21s a large area could be engaged on an almost continuous basis.
These transport aircraft would have an airlift capacity greater than required, smaller aircraft could be used, however this arrangement would allow the whole team to quickly be redeployed to another area. Flying high above the scene the aircraft could act as a relay and link the troops on the ground and local airborne forces back to base, allowing commanders to adjust forces as required.
COIN operations are often required in remote regions where airfields are few and far between, and those that are available are rough and ready. The C-130 and the C-27J can operate in such conditions; but I doubt if the current PC-21 could operate off such strips. So let us hope that the military version also addresses this issue.
Implicit in this mix are ground troops and helicopters. It might be possible to equip the transport aircraft (particularly the C-130), so that the helicopters, the troops and the ground crew could all deployed to a new base at the same time. Leapfrogging from forward base to forward base (clearing the new base from the old) would allow limited forces to control huge areas. After reoccupying a base regular logistic support channels could be used to re-supply the new base.
Before departing an old base, using modern equipment it should be easy to leave a few things around that would discourage intruders. With the protection of quick reaction support a few troops could remain on each forward base to “feed the dog”.
The ability to quickly deploy to an area with a full range of capability is compelling.
For countries with long borders and small budgets, with rough forward bases, using mobile self-contained agile forces, may be a cost effective way of making the opposition kept their heads down.
Chris
nfloorl: 
