There are 43 Oklahoma state parks with RV campsites. Check out
Oklahoma Map - State Parks | TravelOK.com - Oklahoma's Official Travel & Tourism Site. One glitch on the map; The icon for Great Plains State Park is actually misplaced; it should be between Altus and Lawton, near the town of Snyder. The icon is actually where the Quartz Mountain Nature Park, on the shore of Lake Altus-Lugert, is located. There's camping there, too, but Lake Altus-Lugert is currently about 16 feet below normal, leaving all of the boat ramps high and dry, so I can't recommend that one at this time.
Not a State Park, but there is also camping at Lake Carl Blackwell. The lake is owned by Oklahoma State University (my
alma mater). You can get info at
Oklahoma State University.
I used to live in Oklahoma when I was a young'un, but haven't been camping there since I graduated from Oklahoma State. Hope to hit an Oklahoma State Park sometime this year (maybe Hochatown SP on Broken Bow Lake), when I can wrangle a whole week off from work to make it worth driving that far.