To all those warning of sins an prohibitions of using secular courts:
Engaging an attorney does not mean this will go to court. Less than 10% of client activity results in a lawsuit.
The OP should see a land use attorney. This specialist will draft and send a letter to the abutting landowner pointing out the civil laws and regulations that are being violated. Also, potential civil fines and liability in tort law if the offending act does not cease immediately. An offer to allow temporary trespass in exchange for compensation could be offered.
