You actually hit on the reason and didn't even realize it. It has nothing to do with drones or camo. They're heating up the airframes for hot fluid servicing.

Normally this isn't a big problem, but if the aircraft sit for too long it helps in servicing them to heat things up to help move any settled "sludge" around in the various tanks and lines. It's kind of an indication these aircraft are sitting too long without being flown.

Thankfully for them they probably have plenty of garbage tires lying around after letting all their trucks sit for too long without being driven.