Very interesting!!Earl I am sorry but i hadn't been paying much attention to the thread so i am not sure is exactly what you are trying to stop and where it is occuring but i did notice you mention that you were told you had to get permission to film which i do have some knowledge about and can be some help. The easy way to get around getting permission is to place a notice on your house stating that security monitoring devices may be in use.
In regards to the range and what can be picked up from my experience even if you were to encroach on his property there is bugger all that can be done about it. I had a situation where neighbouring shops in an arcade were broken into while i was in the vicinity working back late at night. I didn't realise that anything was happening until the next day the police interviewed me because they had seen that i was in the building at the time. When i asked them how they knew this it was because all my movements were captured on next doors camera while i didn't have anything to hide it did make me question the legality the general consensus was that it is is normally only the origin of the camera that is taken into account not how far the view takes into account as it varies so much between models.
If you are looking for a reasonably low cost solution bunnings and dick smith etc sell a lot of the swann security products which are still reaonable but are at the budget end of it