We stayed for a week at the end of September and it was great! Very quiet park, mostly all long-term residents. I think I saw a total of 3 people the whole time we were there! There is no office, laundry, or restrooms, so you have to be self-contained but for the price, it's perfect!
The sunrises and sunsets were gorgeous and there's almost no light at night which provides a fantastic view of the night sky. There are tons of deer and wild turkeys roaming around throughout the park, very cool! It's about 45 minutes from Devil's Tower, perfect for an evening visit. Conveniently located off 90 in a very quiet area - would stay again!