West Texas is Rockdocking Country!
West Texas is boondocking country! There are plenty of Federal and State Parks and since you are looking... just go and you will get there sooner than you think. Just be prepared with provisions, water, propane and maps. Just pick an area you think could be interesting, hook up the trailer and see where you end up! We have camped in Texas only once, north of Amarillo to the Alibates Flint Quarry. Well... it was closed that time of year, it was hotter than a furnace and we kept heading west since then... end of story.
You will learn where you do not want to return a second time! You will find special spots that you want to return, and return in the future. You will branch out and discover one area has more camping options that could take a dozen trips to explore.
Trust me. If you think all of us have a plan before we get to some place... you are wrong. Stay above 3,000 feet elevation where the air is drier, so the heat and humidity do not ruin your experience for the family. When you hear the air popping against the window, you know you are getting there...