Here's what you do! Put a motion light out there, but don't put bulbs in it. Put one of those electrical plug in's in it and run a extension cord into the house with a light or a buzzer connected to it! Motion detector goes off and you'll know it, grab your shotgun and cell phone! Local farmer had a problem with coyotes and raccoons getting into the chicken and rabbit pens, and he did this set up! Worked like a charm.
Or, set it up with a camcorder and video tape them trying to get in! That way you can take it to the police! It might be that these guys are breaking into alot of peoples rigs! And this might be the evidence they are looking for!!