It will be crowded, but Big Bend is a big park. Going up to the Basin will take patience, but going for even a short hike will keep you away from crowds (unless you do the very popular hikes from the Basin). Take some time to visit Big Bend Ranch State Park. Part of it is available along Hwy 170 going towards Presidio which you will be driving any way or you will be missing an incredible drive. Take a day and drive into the state park - the road is long and unpaved but the main road is passable for a passenger car. From the end of the pavement to the ranger station is about 27 miles and you will be going slow, but you don't have to go all the way in.
You mentioned landscape and nightscape photography. Both are amazing in that part of Texas. You will almost certainly also see plenty of birds like road runners, hawks and neotropical migrants at that time of year. You will probably also see javalinas (look like pigs but are unrelated), coyotes, mule deer, maybe a bear or a mountain lion. Tons of reptiles, just keep your eyes open.
It is a great place to visit. I hope you have a great time.
Tim