A campfire would be nice but, it so dark out there that you hardly need one to see because the moon and stars are gigantic and it would kill the amazing view of the stars. I've never once missed having a fire while camping there. Big Bend has "the darkest sky in the lower 48" IDA Gold Tier Designation - Big Bend National Park (U.S. National Park Service)
I like to check this website Heavens-Above
before we go to know what we can expect to see while there. A few times we've been lucky and seen some meteor showers or planets.
There is a ton and a half to do in the national park. You can drive all day on dirt and think about the old miners and ranchers who used those "roads", you can hike all day, or float the river. You've got everything from mountains and trees to empty deserts and a river with an international border to boot. It's always funny to me when we see the border, especially when you see cattle walking across the river for some AMERICAN grass, and you get to thinking about how insignificant it is.
The best wheeling is the Black Gap Road, the River Road, parts of Glenn Springs, and Old Oar road. Unless it's rained you should be fine in any sort of jeep. The only thing to know really is that your really on your own, if you forgot something well sorry Charlie your 200 miles or so from the nearest walmart. There are two places to get gas in the park though luckily so there's no need to worry about carrying extra. Just top up every chance you get.
If you have any specificish questions lemme know.