My two cents. Anything that may injure an innocent party could get you sued. (Even a not so innocent party.) If a little kid gets dowsed by your motion activated sprinkler or burned by your pepper, you will be the one with angry neighbors knocking on your door.
I like the game camera. Can you just set your video cam up in a window and put in a long playing tape? Then go knock on the neighbor's door with the proof.
