A few thoughts, isn't that in the SBNF? If it is in SBNF you have some options if you can't rent a campsite for the night. SBNF has "Yellow Post" sites that are not in Campgrounds, but usually found off the beaten path up some Forest Service Roads. You can have a campfire at Yellow Post Sites, but I think you need to stop by the Ranger Station and get a fire permit, which IIRC is not as much as a campsite, and you usually won't have any neighbors nearby. Another option is dispersed camping, and the only drawback is you can't have a fire, and must use a propane stove. Hope it all works out, have a good time and be safe.