I did leave my portable stand up this year and had almost the same problem as you midwest.I was after a big buck I had seen earlier in the season.Another hunter would show up in the evening with his portable, walk past me and I could here him set up his stand about 75yds from mine.I even moved my stand about 200 yds away,and sure enough here he comes in the evening and sets up not far from me.I told my wife I thought he was following me.So sometimes even if you leave your stand up guys will set up where ever they want to with no regard to other hunters.