- The closest thing to you will sam Sam Houston national forest. There are hundred of miles of forest service roads in there that could be strung together into a few days of riding. There are also about 70 miles of single/double track on the western side (with Huntsville state park) that are shared with ATVs and dirt bikes.
- There's Big Bend [ranch] state park (not the national park). A few documented trips: http://whileoutriding.com/2012/02/15/back-in-the-chihuahuan-desert-bikepacking-in-big-bend/, http://www.bikepacking.net/forum/index.php?topic=1777.0. This is on my to-do list for the near future.