Sniper Monkeys, that's it. They could climb the trees and snipe down from above, unseen. Or throw grenades.
How about a really silly idea? Why don't the Civil Police and RAF Police arrest these vandals and let the courts deal with them properly? If the judges made an example of these criminals there would be less of it in the future. Make the stupid cow do community service; she could repaint the squadron for a start, it's a right mess. Publish her address and when somebody from Leuchars fancies a day out they can break into her house and damage her stuff, and then get away with it because they claim they did it as a protest.
Sniper monkeys.