I don't understand the "terrorist/vandalism" actions. Based on laws (here in NY), that action would put you at risk litigation (and likely loose for creating a hazard - you want to loose your land for that?). Post your land (your laws may be different, but then it becomes off limits). Put a sign on it telling him to leave or take it down. Maybe check it for use (lots of ways to do that on the sly). If use continues you now have willful violation, and get the law involved or if you encounter him, just ask him to leave. I think diplomacy works better than flying off the handle. Next thing you know, something ugly happens. Play it safe.
just my opinion, no debate needed
BobW