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....
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