I have been face with similar situations: I had been given permission to hunt several sections of land in Northern Ca. Come to find out, another guy also had permission to hunt the land and had bee for a couple years.
I simply contacted the other guy and informed him that I had recently been given permission to hunt the land as well and asked him if he thought the land, about 12000+- acres would support another hunter.
He said that the land was over-run with coyotes and digger squirrels and invited me out on his next hunt. He showed me around the property and we came to a compromise using a road that divided the land we were able to split it in half.
As it worked out, everytime we bumped into each other, we crammed all of our gear into one rig and hunted together.
In the case of "public" land there just isn't anything you can do about that.
My trapline runs about 50 road miles which includes stretches of five rivers/creeks. There isn't anything I can do about keeping others off of most of my line. I am just forced to improve my skill which I have so far successfully done.
Last year for example, there were two other trappers in our area. Despite that, we were able to take a dozen wolves, a limit of beaver and almost fifty mink. One of the other gus took one wolf and about a dozen mink. The other caught about ten mink.
Fact is, I try not to overstep my bounds, but on the other, I don't twist off if I find someone calling in my favorite hot spot. I just let them know how long I have been around and tell them about some other spot that I heard was loaded with critters, wink wink. AW