We went to Hill City, ND in the Black Hills National Forest Sept 9 - 18, 2018 and it was our first long trip as newbies in our 2018 Alante 26X. Started from St. Louis area, and our half way point is Onawa, IA on I-29 where we found a wonderful overnight RV park right next to the highway called On-Ur-Wa. We highly recommend staying there: Good Sam discount members, owners live on property, impeccably clean, behind a gas station and McDonalds, and about 200 ft from the highway exit off the outer road.
On~Ur~Wa RV Park
In the Black Hills National Forest we stayed at Horse Thief Campground & RV Resort. We highly recommend this place as well if you need full hook ups. If you're willing to go the state park route, Custard State Park has a few sites with electric and water/dump stations.
Home
REASONS WE WOULD STAY AT HORSE THIEF CAMPGROUND AGAIN= centrally located, great views (tucked back from the road), all spots are shaded, lots of wild life, family friendly (not a party spot), clean bathrooms and laundry, owner and one or two of the hands live on site, deer and wild life close by, about 3 miles from the town of Hill City so groceries/restaurants/awesome candy store and coffee shop close by, AND economical, so to me you hit the mother load with this spot. I recommend you Google Earth the RV spots as every single other one we saw in the area (with the exception of in Custard State Park) was lacking shade and some were just bare minimums.
THINGS WE WOULD DO DIFFERENT = Stop at The Badlands National Park first and stay 2 nights in one of their spots. There are no trees and supposedly a no lights during quiet time policy, so if you get a cloudless night the stars are spectacular. It takes 2 days to really enjoy every thing the Badlands has to offer especially if one of your days is cloudy/rainy.