We are hoping to meet our son and his family to go to the Christian music festival this Labor Day weekend, Sept. 4-6, but we are having trouble finding a camping spot. The state parks nearby are full, as well as the Red Barn & Countryside. Does anyone know campgrounds in or nearby Sioux Falls we could try? The local KOA thought they might have room--how bad/good are they? Maybe an off-the-beaten path campground or one that's so small most people don't know about it would still have something available, if we're lucky. Thanks for any help you can give.