Comanche Park is just outside Custer, South Dakota. It’s open seasonally but it looks like a few spots are before the gate. The campground was pretty empty during the week but the host said it was full on the weekend- consider making a reservation. The sites are large without much vegetation between them. We were far enough apart that it still felt private. A picnic table and fire pit are standard. Vault toilets are spread throughout. There is water available but I would consider your options. The host said they get bottled water when I asked about the quality. 

The draw to this campground is that it’s close to Custer State Park. We arrived midday, set up and still had time to drive the wildlife scenic highway and the scenic drive out of Custer towards Mt. Rushmore and Crazy Horse. We were feet from a bison herd and arms length away from donkeys. Returning in time to make dinner was great. Tomorrow we’ll leave early and do another drive and hike in Custer State Park. 

Comanche Park is a good campground to use as a base when you explore the area.