I don't have an answer to your question, but I agree that it's messed up that people mess with stuff like that. The other day I was leaving walmart when I saw this couple standing near a really nice chopper. They were taking pictures of it, and then the wife just hops on it and the husband takes a pic of her on the bike. Then they got up and walked off. I really don't think it was their bike. People suck
Anyway, I saw someone on here that had a locking gas cap. Maybe that would be a good alternative? Also there are motion-alarms you can get for your bike. Would go off if someone moved it. Might be a good deterrent as well.