If one had the means, it would be interesting to cook up ways to harass Blackwater without direct face-to-face ground engagement. Honeypot traps rigged with pink exploding dye pack, for starters?
Itching powder in the laundry facilities or urishol (poison ivy) in the porta-potties?
Whatever could be done without direct risk of getting shot.
Just pipe dreaming here. Really not looking for an armchair treatise on sabotage and warfare.