My 2 acre semi rural property was a constant headache, one that almost cost me my life (a story for another day) . The neighbors tried every trick in the book to continue using my property as they saw fit. Including, but not limited to, horses with bad people, a motocross, tractor, swamp buggy, and ATV track, a lovers-lane, a pass-through to the everglades, and a drive by shooting range.
We tried everything, cameras, dogs, signs, spikes, cables, mounds of dirt, you name it. Only one thing worked. A quality fence and powered/locked gate with 2 courses of barbed wire on top of both the fence and gate.
Eventually, the trouble subsided, as the injuries mounted.