Custer State Park is one of our favorites in entire US. If at all possible try to stay there. The park is huge, the sites are not crammed in like many commercial parks. They have reasonably priced sites, maybe you could get a site for the trailer and the RV. I think most are back in but you have plenty of room. There is wildlife galore throughout the park and also have very nice restuarants reasonably priced in the park, plus lots to do including tours. Stay away from the Deadwood KOA, nice location in Deadwood but you are really crammed in. We paid for 3 days and left after one night and forfeited any refund.