Spaas Creek area west of RRG. You can access some ridgetop roads which are partially closed to motor vehicles. Go to Fagan, KY, make a right at the top of the hill (looks like a driveway) and have fun.
I used to ride near Fixer on oil roads a lot too. There are tons of possibilities there.
The Sheltowee Trace south of Natural Bridge can be accessed from Standing Rock and there are lots of 4WD roads in the area.