If you are passing anywhere near Lawton, OK (just southwest of Oklahoma City) I recommend stopping at the Wichita Mountains Game Preserve.
You will be driving on open range in some of the prettiest mountains in the Mid-West among Buffalo, Herds of Elk, gaggles of Prarie Dogs, and Long Horn Cattle.
There is good camping in the Federal Park (that abbuts the Ft Sill Army Post), and walk-in campers are accommodated along with RVers (20, 30, and 50 amp hook-ups for $12) or no hook-up for $6. Clean restrooms and free showers as well as RV dumping are available.
Fishing and hunting, along with great hiking and rock climbing are available.
In addition, there is an interesting site called the "Holy City" inside the Preserve that was built in 1935 by volunteers from native rocks and materials, and is active today as well with Easter Services in addition to regular services.
If you want to see some photos from our recent visit (my first was in 1972 when stationed at nearby Altus AF
, go to:
The park's website is: