The weather is pretty nice, in my opinion.  Lots of sunny days, which is great for solar, but it helps to set up some kind of shade if a group is hanging out for an extended period of time.  Also, being "high desert" and generally low humidity, there is a relatively large temperature change between 2pm and 2am.  Check out the yearly weather for Terlingua, Zip code 79852, for the full story.

By the way, I'm pretty sure many kinds of Ultralights would be able to take off and land on the main road without too much difficulty… especially the "parachute w/a fan on the back" kinds, gyrocopters, etc..  And no pilot license required for some kinds - although common sense says one had better be trained and/or experienced before just "going for it".  There is no lack of amazing scenery around the Big Bend area to fly over.  There is also both a (currently rough) dirt strip airport, and a quite nice paved one, within 20-45 minutes drive.