there is a small campground right after you cross the bridge on the Yellowstone River as if you were heading towards Red Lodge. Not sure about hook ups and fees or cleanliness, but it is the closest one that I know of.
Traveling Whitehouse
2006 Keystone Raptor 3612DS
2004 Chevrolet Silverado 3500 CC LB DRW Duramax LLY 4x4
Reese 20K Hitch
Prodigy Brake Control
2007 Honda Rincon & 2000 Honda Rancher
We spent one night at the above mentioned park by the river. We were OK, but we felt a tad uneasy because of a few of our neighbors. This was two years ago, before the economic downturn, but it appeared there were people there living out of their cars. I would definitely check it out before staying there. I didn't look in the restrooms, so I can't say how they were. We had 30 amp and water, but the exact campsites were a little difficult to figure out. But we did find room for our 38' motorhome.