We stayed at Yellowstone RV park in Gardiner with our 36 ft 5 wheel and a medium duty truck and it was right above the river giving fantastic views of the boaters floating down. It was about a couple miles from the entrance to the park and easy to get in and out. The only drawback was the entrance to the park is a fairly steep decent down a dirt road, everyone does it but a bit intimidating when first being seen. You will go down and back up in whatever rig your in. Not a resort, but worked well for the week we were there.
