I finished this evaluation yesterday. I believe that the only FHU in Yellowstone is Fishing Bridge and it is also 54$/(it says 46$+ taxes) night with taxes. The West Yellowstone parks are way less. Most have good reviews, but get to
RVpark Reviews and read them yourself. I just added the link the YNP parks, but you have to go back and select Montana for the West Yellowstone parks.
There will be two road closures after labor day. They are very serious and almost crashed our plan. One is the road between West Thumb and Old Faithful and the other is the road that connects Mamouth to Norris. You may chose to look at maps to see how much this will upset things. It says to expect other delays for road work.
As we will be curtailing other aspects of the excursion and not having transportation other than our little coach, the choice was very difficult. We elected to reserve a place at Fishing Bridge. We will be there when they roll up the sidewalks for the winter. We expect that we will only have this one shot. We have to make it count.
Matt