The park is right off the highway in a pretty desolate part of South Dakota. It was the end of the season, and so although I didn't expect a crowd, I also didn't expect to be the only person there at 1 pm.
Severe thunderstorms had followed me for the preceding three days, meaning that I was tired and ready to plug in, put on fuzzy socks, and read a good book, but when I pulled into this KOA, the office was dark, and there wasn't another soul in the campground. I pulled through anyway since I had already paid, only to find that most of the spaces were flooded. I have a 1-ton camper van with rear wheel drive and didn't want to get stuck, so I pulled back around to the front of the park. About 1/2 hour later, another camper couple showed up, and then a third. There was no answer to our phone calls to the owners, and since there wasn't another campground for 20 or so miles, we all decided just to stay put and hope the owners showed up. Finally, at 2 pm, they showed up and sorted everything out. Although they live on the property, they don't respond to calls until after 2 pm.
Evidently, the storms were a rarity and caught everyone off guard. It may well be that I would have had a better experience had the weather been better and/or during peak season. My only suggestion to the owners is to please return calls/answer the phone. Travellers are usually tired and unfamiliar with the areas, so a reassuring voice can be crucial.
They do have a store of sorts, but it's minimal. I'm not sure I would stay here again.