This happened to me nearly 20 years ago. I was wondering how you all would have handled it.
I have a 40 of hunting property up in Douglas Co (close to 2 hours north of where I live). On one side of me is more private land, on the other is papermill land (open to public). I put up a ladderstand on papermill land for bow season because the enclosed stands on our land are not conducive to drawing a bow, plus the deer like to hang in the pines and scrub during the warmer weather.
So, one Saturday afternoon sit I was successful on a buck. It was warmer, so spent the next day skinning/quartering/cutting. Following weekend I went back up for the day to retrieve my stand.
Hiked up on the ridge and found someone sitting in it, hunting. I mentioned that he was sitting in my stand, he said "This is public property, I can sit in it if I want legally." I told him "Yes, you're correct LEGALLY but ethically is another question, and I just drove 2 hours to take it down because I got my deer last weekend and I'm not waiting around."
What would you have done?
