My advice is to call LE first. Here in Iowa, our land has to be posted in order for it to be trespassing. But I would call the local sheriff's office and ask them. If you're land needs to be posted and it wasn't before the stand was placed, then I would try to catch the person hunting there and ask them to leave. As a landowner myself, I'm am concerned that you have a more serious problem than just an unwanted hunter. If this person comes on your property and injures himself, or worse, you or someone else, they can sue you and you lose everything. Be smart. Find out what the law is in your state and get it on your side. Good luck.