Its only a couple of hours drive to the north-east from where the Lone Star Enduro was held(100 miles or so). I have not riden there, but have been through the area. I think it would be a lot of the same, maybe a bit more rocky. I would go with an intermedate tire, but that's just me.
Last year it was deep, deep sand for the first 1/3 then turned into rolling hills and gullys. There was one section near the beginning that was about a half mile long section of sand dunes covered with cactus. Each dune was about 15 to 20 foot tall. It was pretty cool because as you topped a dune you could look forward in the distance and see a number of other riders topping dunes in front of you. The was also a couple of real sandy uphills that swallowed some riders...especially the one right after the first gas stop.