Loved Yellowstone. Was one of my favorite vacations. we didn't have a camper at the time,rode the motorcycle from Iowa
So I am not sure about campgrounds.
There is the dinosauer dig in Hill City SD that we liked if you have time. The needles are fun to see while there.
Tons of stuff to see in Yellowstone. I was disappointed in Old Faithful. I guess everyone has to see it one time,but I wouldn't waste the time again. there are more fun geysers to see in my opinion.
Have a great time