those two are insane...I'm sorry you have to go through that. Cameras are a great idea too. I can't imagine how crappy that feels to have a lawyer say "it's like quicksand". I don't know if you can, but maybe ask a lawyer if you can sue them for money for harrasmet and property damage? That might scare them enough, or maybe jeopardize how much money they have to spend on gas money to follow you and rent or mortgage payment to live near you. That might be really obscure, but it might scare them to stop.
Well..in a non-aggressive manner, I'd carry mace or pepper spray on you and with your family....next time they are in your driveway or what not or on your property giving you crap, spray them. It would be a good way to not get physical, but to make them get off your property. However, I understand if you're scared that might escalate things. or you could get an invisible fence for your dogs (if that works wiith GSD). I bet that would scare the crap out of them...but as the flip side to that, it could put your dogs in danger too if they decide to hurt them. I wish i could help...