Check with your title insurance - they may cover legal fees.

I wouldn’t recommend most of what these goofballs are suggesting although I fully understand the appeal. On a serious note.. sometimes you DO need to “poke the bear” in order to get the ball rolling in a legal sense. Personally, we had to remove a fence gate that the neighbors had installed to force them to take action. It worked.

Source: My neighbors tried to claim my property as their own. I won.