Just on the other side of the Christmas Mountains was Big Bend National Park.
There was a back-country road from Terlingua Ranch into the park, but it was washed out a couple years ago and is too remote to bother fixing it.
Plus, under Trump there were more Border Patrols checkpoints on the main roads and I don't think they wanted to monitor the 4-wheel drive roads.
Goat Mountain is a volcanic peak located in the Sierra Quemada in the southern Chisos Mountains of Big Bend National Park.