Location is everything. Chisos Basin Campground is a very close quarter campsite with very little parking for large vehicles. Even when you are within the recommended length according to the .gov site, you may still be sticking out on the road or parked along the edge of the road. This is not a "secluded" campsite.. The winds can get up and disturb your gears across the campground if your not carful.
But Locations is everything. It's high in the "mountains" with grand views, wild animals, and close to a lot of trailheads. There is a small store up the hill and a restaurant. The sunsets are amazing from the basin. The mountain cliffs will turn bright orange and red with the right light. There are bears, cats, coyotes, pigs, and foxes. We even saw a small ground bird that wound visited our camp, scratching at the grass and brush for seeds. We saw a fox one evening dart across the road.
Big Bend is a Dark-Skys Park, so don't be that one guy that leaves his exterior camper lights on all night. The stars at night are big and bright, and absolutely amazing!! We laid there looking through the sky light for half the night. They will keep you awake.. So many and oh so bright!!
If you want secluded, look to the back row at Rio Grande campsite or one of the backcountry site. Cottonwood is quite and peaceful too. Spring is best, summers are rough, hot and can be dangerous for the unprepared. The beast season is Nov - March/April. The best time is when the cactus blooms around spring break.
Enjoy and be prepared, it is a desert, but oh what a beautiful desert she is...