Just another option if it has not been mentioned and if you are towing a vehicle(I didn't notice what type of RV you had) but Baker's Hole outside of West Yellowstone does accept Golden Age, they do have water and electric sites and as I recall, they are first come, first served. We stayed their a coupe years ago and used it as our base camp...it required more driving but it sure is a beautiful CG right next to the Madison River. I realize that's still taking a chance on not getting a spot but thought I'd mention it anyways.
