It may be costly, but consider fencing in entire yard, or at least place some big rocks around perimiter where kids are riding on your property.
Motion detecting lights by your doorways (if you do not already have some) can at least give ya some warning if they are getting too close to your home (and if attached to the house, hopefully they can't/won't try and break them).
Being out in the country, I, too, recommend you getting a good sized and well trained dog and the cam-corder is a good idea also.
Good luck, I know how miserable a lousy neighbor can make your life. We finally moved....
We're planning on planting some big bushes from the front edge of our fence down to the edge of our property by the road. We're also going to be putting up the motion detecting lights. My concern is that he'll just get one of the kids to ride their four-wheeler right through our bushes, if we plant them.
I really hope we don't have to move. I really love my house and the other neighbors don't bother anyone. He's the only pain on this street and loves directing his self-hatred at us since he found out his property line wasn't where he thought it was.