We are planning on making the Black Hills the first stop on our trip and arrive on July 22nd. Hoping to get in front of the Sturgis madness to follow and be on our way down the road before most of the bikes show up!
The National Forest website mentions that disbursed camping is available in the north and the south, but is short on details. About 20 years ago we did spend a few days on a beautiful dispersed site, but I don't have much confidence that I could find it again. I don't recall seeing very many spots to camp dispersed though. We may well end up in a NF designated campground and that would be fine too.