I finally figured it out. To stop it on your land, ask Pete (or any friend) to park a pickup just off the road at the prime walking-in/out spot. The yayhoos will think it's one of their own, already set up, and they'll go somewhere else.
jeffp, you don't need to change-- unless you're a yayhoo, and I don't care if they ever change anyway. I just want them to go away.