You are probably looking at a couple hrs+ West to get into good Rio hunting or going North to Oklahoma.
I would go West to get away from the big city hunters. Call a warden in the area you want to focus on and see if they know any land owners that need the turkeys hunted on their place. Deer hunting in TX is much more difficult, but many land owners don't care for turkeys and most of the deer hunters could care less about hunting them. You want water, a few trees, and wheat or rye fields. If you find those 3 in the deserty areas of North Texas, you'll find Rios most of the time.
The game wardens sometimes know of landowners that want turkey hunters on their place. Once you get on one place, it's usually easy to get in good with the neighbors.