Not to hijack your thread, but I have something closely related. Have hunted an area 3 of the last 5 years. Twice w/bow and once w/rifle. There is an outfitter nearby and he has put treestands up on every waterhole in the area (14 that my partner and I have found).
Problem is that they are chained up and left year-round to "claim" the spot so one of his guides says. We have gone in there spring and summer and they are always up. Only rarely do we see a hunter at one in season.
So what do I do? Put my own stand up, (maybe in a tree right next to them) or find a new area? It is ALL National Forest.
John
In Idaho, it's illegal to leave a portable stand up overnight. Permanent stands on public land are 1st come, 1st served. That doesn't mean the guy who put it up won't cause you problems, though.