If the camera isn't viable, how about semi-gloss white the whole thing?
A roller/pan will stay fresh for about a week in the fridge when wrapped up with a single sheet of aluminum foil. Spritz with water and roll in pan to refresh. If it's 1-2 painters, they might get the drift and give up.
If you want to confront the perps, they've got motion detector outdoor lights(remove lights) that sends a wireless signal to an alarm box inside in the house.
Paintball gun using the oil-based markers from the roof. Taste of their own medicine
