No big dog. If the kid gets bit you will be in more trouble then you can shake a stick at and you will feel awful.
You will likely win out over the legal trouble but that kind of thing can drag on and if the police are not on your side that makes it worse.
Getting together with your neighbors is a good idea. A united front makes it much easier for all concerned.
And the video camera is a wonderful idea
How sad that while he abuses our hearing and peace with his loud music and other abuse, we have to now worry about him sending kids into our yard. I think the camcorder idea is a good one. My husband was also thinking about those cameras that you mount on your house.