Open year round, but dry camping w electric after mid-Oct, first come first serve. Pretty empty weekend of Halloween when we stayed. Mostly quiet, some highway noise even inside RV, some folks live behind campground in trailers and there was lots of slow traffic thru the campground, even later at night. Able to dump RV, but they were shutting off the water Oct 31 due to forecasted freezing temps, so definitely dry camping. Not all sites have all amps for hookups, so check the post before you set up. We had to move to a different site because the 20 Amp was not hot and we didn't have our 50 Amp adapter, no 30amp on the post. We had to poke around for a 20amp that worked and move there. Even the 30 Amp didn't work nearby.
Gas station across the street is open but has strange hours in off season, maybe 9-3? Pay at pump appears to work 24 hrs as of Oct 31, 2021.
8 minute drive to entrance of Badlands makes it a good location, would stay here again in fall/winter just for the electric as the park campgrounds are non-electric in the off season.