I had squatter too. It was an old guy, father of my buyer. He had broken down RV parked on my property living there. I couldn’t get him off the property. He was living there. I didn’t yell at him or anything. He told me he has no place to go.
So I told him to keep looking for something. And I just moved on with my other deals kind of hoping the situation will solve itself.
I got lucky. Nearby farmer bought my land for cash contacting me and helped the old gentleman tow his RV to some camping ground. The guy who bought it for cash solved the problem.
The simplest solution with squatter I see this: don’t waste energy and resources on it anymore. Let the situation solve itself. Keep marketing it, look for right buyer who’s not afraid to get rid of squatter.
After some time if no one is interested and squatter is still there: drop price even more.
make the price irresistibly cheap. Cheaper than you had before. Deep bottom cheap. And let the buyer deal with it. You’ll not profit as much but you’ll get rid off it.
The key in my opinion is to: not waste any more mental, emotional, negative energy on it. Move on working on your other deals.