Nice to see you over here, Fog. Since Fog didn't mention it, the only place in the OKC area that I've found to wheel thus far, is along the south side of the Canadian river (south of Reno) between Macarthur and Meridian. You can access it from Enterprise drive, driving westbound from Meridian, it opens up to a dirt trail, but you will have to cross the river over the spillway to get to the trails on the south side of the river. (unless the river is swelled, its not really that tough)
You can get to them from Macarthur by driving south of the river; you will find a dirt trail leading eastbound from Macarthur just about across the street from the 7-11 there; its a little rough going until you get back on flat land from the heavy-hitters that have dug deep ruts with their excessively lifted trucks, but if you take it slow, you can drive between the ruts.
I've heard that there's another spot near Reno and County Line Road (also by the river) but I haven't had a chance to check it out yet myself. If I do, I'll post about it here.