I took a SPOT gen 4 in case of emergencies and to check in with the wife. Worked great. Something tells me that if you had an actual emergency, someone MAY show up between 72 hours to 2 months.
Roads are not a big deal. You'll be fine with your rig. Some of the trails may give you pinstripes - not many, just watch for that. As notorious as Black Gap's reputation, there is only one shelf that may be a challenge. Many are sand but it's packed. Lots of washboard, not difficult but annoying.
They give you a paper map when you register. It was handy to have. The miles between the different roads are marked on the map. You might see that you take the 2nd turn on your right, but that is actually 30 miles.
The BB parks are gigantic. Once you're south of I-10 make sure you get gas and have a reserve. There is fuel, ice, water and snack foods in Terlingua at the west gate and Panther Junction at the park headquarters.
Chisos Basin is an improved campsite but spaces are close together. Even if you don't camp there it's still worth a drive by. You will have cell service here. Back country camping is where it's at but Chisos was good to do once.
River Road between Lajitas and Presidio (RR170). It is paved. It's 55 miles one way and only a couple of turn off points. This road and views are on the same level as PCH in CA. Do it if time permits. If time doesn't permit then do it anyway.
Everything you will see is incredible. It's a really beautiful part of our country. If you are a photographer, get ready.
ETA: The star watching party at McDonald Observatory is great. If you can catch it with a no or late rising moon it's even better.
https://mcdonaldobservatory.org/visitors/programs/evening-programs Attached File Attached File Attached File Attached File Attached File