To the OP: You will find almost no boondocking areas, although there are places on the beach at Padre Island. Not where I would want to spend the Winter. It will be very hot in September and October with relief coming in late November. You may be surprised at what you find in the RGV (Rio Grande Valley of Texas) For example; we must have 20-30 Walmarts, which surprises some folks. Also, it not a "Valley" in the usual sense. Just a desolate dirty strip of land along the Rio Grande River that is far enough south to be somewhat warm in the Winter. Come on down.