We stayed at the Cottonwood CG inside the NP. Looking at RVParkReviews now, it looks like a lot of the oil field workers have invaded the area. So the NP might be your best and maybe even only choice. Medora itself was nice and clean, prices on the high side thou as it is (was?) mostly a tourist town. But there is plenty to see and do inside the NP. We had planned on heading to the north unit, but were warned off by several different people about the lack of CG's and very heavy truck traffic (think broken windshield). So we headed west into MT instead. To be more specific, we were told to avoid US-2 anywhere near the MT / ND border area due to the oil field work going on.
2006 Fleetwood Bounder 35E