ULPT request: how to stop people from turning around on parking pad

I live in a small neighborhood near a semi-popular historic distric area. The street i live on goes up a hill, plateaus, goes down a hill, turns sharply and goes back out the main drag (basically a big U with a part of the U on a hill). Its a narrow residential street. The only people who use it are residents, delivery drivers and people who make wrong turns.

I live at the end of the plateau and we regularly go outside to let people trying to do awkward U turns know that yes, the road keeps going, yes they can go down the hill, etc.

Well, apparently when we are not home, people use our small parking pad to turn around. This would not be a problem, except that we've been getting damage to things near/on the parking pad and to the pad itself.

How do we keep people from using our parking pad without damaging cars (and getting sued) that also isn't a pain for us to deal with. I don't really want to get out my car to deal with a gate, for instance.

I was thinking fake driveway spikes. Any other suggestions?