A great road to enjoy. But not on to breeze through at 55 mph. More like 25-30 in some sections.
As mentioned one steep grade. There are a few dry campground locations along the road and some hiking trails. Much of the road passes thru the Big Bend State Ranch Park. Float trips run along that section of the Rio Grande.
There an old movie set just after leaving Lajitas that we found interesting. Right after you leave the river near Randolph is Forest Leaton State Historical Park. An excellent place to stop. Well worth a couple hours.
Fuel - you are in a “boonie tax” area. Prices are high. Fill up at Alpine which is usually 10-20% higher than the state average. The entire loop from Alpine to Terlingua to Presidio to Marfa is 205 miles.
First fuel is at Study Butte where TX 118 and FM 1170 meet - 78 miles from Alpine. About 15-25% higher than Alpine.
There is a possibility that a small store in Lajitas might have fuel at 95 miles. I would not count upon it.
A few stations in Presidio. 145 miles into the trip. A little less than 70 miles past Study Butte. Fuel will be between Alpine and Study Butte price wise. Then 60 miles north to Marfa where fuel will cost close to Alpine.
Since your profile says you are in Mission, you already know about miles and miles of miles and miles of nothing driving in Texas. And none of the drives on the loop you described are longer as individual legs without fuel than you already have to drive to get out of the RGV.
