You may be in luck (at least if you're in eastern OK). There's a
rally coming up in mid-Sept. just over in AR, close to Fort Smith.
http://www.fiberglassrv.com/forums/f...6-a-73615.html
Not sure if there are any campsites left, but at least a couple of sites are non-reservable. One year we were able to double up in sites, too... not sure if the park nixed that or if it's still permitted.