I had a similar thing one time myself. I had just started to hunt some land and the owner told me that I would be the only one alowed to hunt and if I seen any one have them leave or call the law. Well I scouted and set my stands up and about three weeks into the season I see a stand. Its old and well used. I asked the farmer about it and he said one guy used to hunt a few years back but never comes around any more. I left that stand up for one year with the posibility it was the guys that used to hunt and maybe he would come back and get his stand and maybe I just missed it when I did my scouting, after one year I took it down and fixed it up since it was well weathered and now I use it. Well after about hunting for five years A nice climbing stand shows up in the area, And its about five hundreds from the property line, This in my mind is tresspassing, so now I have a new stand!