Or even a "private property, no trespassing" sign.

People where I live are illegaly putting such signs up even if the road is public to limit trafic near their homes. I just ignore those.

Maybe just a dead end sign even.

You'd need to get cooperation from the other folks using the road that they'd replace the rope after driving through.

You'd need more cooperation to put a pin-code activated electronic gate up.

But at least the gate would automatically close once they went through.

Just need a gate that exerts tension when it's opened, so it'll drift back to closed if someone forgets. I've crossed a lot of back-country gates, never seen a wild breakdown of the system.

Yes, that's exactly what I was talking about. You can't do that with a rope.