I will add we were up there a week ago and stayed at Buffalo Ridge. It is the old Flinstones place. they are redoing it and it is really pretty nice and lots of room for big rigs and dogs. Because they are new they might still have spots left.
I could not find there website but ended up booking through this black hills vacations site. not the best deal but it is an option.
https://www.blackhillsvacations.com/places-to-stay/campgrounds-rv-parks/supplier/655355-Buffalo-Ridge-Camp-Resort