This is all definitely making me remember why I really like living in the middle of 12 acres, with large trees surrounding our yard and can't even see the road from our house, much less the neighbors. The worst thing that seems to happen here is that the neighbor kids across the road like to blast their stereo in our direction, or occasionally shoot off firecrackers that upset our dogs. Not all that bad, in the grand scheme of things...
Keith, I really do feel for you in this situation; having nearby neighbors that seem bent on making your life miserable is an awful thing. If you have recourse to something like the "good neighbor bond" that Greene described, that could be a great solution; but I honestly don't think escalating the situation is going to make your life any better. Maybe you could find an impartial third party that could sit down with all of you to kind of mediate the situation and come up with some compromises?