Contact the local BLM office in the area. The local folks are sometimes very helpful. They can tell you much more than any internet board. Their advice is free, and they can tell you which BLM maps you actually need. There are areas where BLM has a deal with the renter that provides public a access route across private land.
Be advised that there are quite a few BLM renters that consider the leased BLM land to be theirs and are nasty to the public.