I wouldn' recommend setting any traps. As crazy as it sounds you could be liable. What about the old railroad track bed access sans the tracks? Can you put up a barricade to keep vehicle traffic out and make it a really far walk with the slabs to the vehicle?

How well do you know the caretaker? Is it possible he is in on this?

If pigs could fly bacon would be harder to come by and there would be a lot of damaged trees.