Jim - just a suggestion - think about staying outside the park but close. Since you are wanting to stay within, I'm assuming that you want that FS CG feel. Try Baker's Hole FS CG 2 miles North of West Yellowstone, MT. There are plenty of big rig sites there and most have electricity. There's a water fill up as you pull in but if you miss it, using a "water thief" you can fill up at any faucet throughout. This is one of our favorite close sites and much more roomier than any of the Yellowstone CG's. What we do, since Baker's Hole is a first come, first served CG, is to stay in town at Grizzly, next morning, leaving our fifth wheel at Grizzly, we drive over to Baker's Hole and secure a site, then drive back and get our rig. You may end up staying at Grizzly for the duration. A lot of folks like that RV Park, it's super nice, but we prefer the FS look and feel. Good luck and I hope you get a cancellation so you can stay within Yellowstone.
2011 Bighorn 3055RL, 2011 F350 DRW 6.7L 4x4 Diesel Lariat and Hensley TrailerSaver BD3, 1992 Jeep ZJ and 1978 Coleman Concord Pop-Up for remote camping
Dave & Renee plus (Champ, Molly, Paris, Missy, and Maggie in spirit), Mica, Mabel, and Melton