Depends on which route you take, Trippy shows Bennington (Oklahoma) if you take US-70: https://www.trippy.com/halfway/Lawton-and-Texarkana-TX But I think I might do something more like Sherman (Texas) if you take US-82. You should be able to find a gas station in most towns along the way, so once you figure out the route you're going to take, you can look for the easiest stop off the highway.
