I'd go talk to the guy. All this covert stuff might solve the problem, or more likely it could make it worse. I put a posted sign on a tree beside a ladder stand that was on our property line the first year we owned the farm. The stand was gone a week later.

If my people, who are called by my name, will humble themselves and pray and seek my face and turn from their wicked ways, then will I hear from heaven and will forgive their sin and will heal their land. 2 Chronicles 7:14