Chris, I think you have indeed received divine guidance. It's a brilliant idea. The more official looking the signs are the better they'll work. I'd still back it up with some fire power though. If things get scary, there's nothing like the "kachunk - kachunk" sound of a pump shotgun to make your point. You don't have to fire a shot, just let them know that you're prepared to defend yourself and your posessions.

I shoot mostly double guns, but sometimes I haul out the old Winchester 97 just to hear that wonderful kachunk sound.