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.