Yep, 14-50 only, no fast chargers. We stayed at both Rio Grande Village and Terlingua.We have the Tesla CCS adapter on order now.
But it looks like RV hookups are the main source of electricity in Big Bend. We love to spend the nights in Chisos basin. That looks like the challenging part as there are no RV hookups in the Basin.
PlugShare shows a 6-20 available at Chisos lodge.