Sounds like you have an access road or at least a large walking path or several of them and you really need a barrier like a gate or posts with a chain across and plenty of signage there with signage continuing for a distance. I would also consider signage to include notice that property is heavily hunted and patrolled. If you already have this esp. gates then I don't know what to tell you. "free-spirits" can be difficult to stop but worth the effort as owning and paying taxes should entitle you to decide who uses it and for what. Good luck!!