there's a group of crazies going to ride south of the border in the BB area, I think around March 18. Check at
www.advrider.com, upcoming rides forum. I can't make it that week or the week after, but might be interested in going some other time when my schedule allows. The week that you're planning to go is during spring break for at least some of the college kids. That means all the campgrounds and hotels will be full with teenagers, and there will be a lot of hikers. You may see a few more people than usual on the dirt roads inside the park, outside the park probably not much more traffic off of the pavement would be my guess. The restaurants in Terlingua will probably be full to overflowing too. If you were planning to camp or hotel inside the park, you'll have a tough time finding a spot, plan on waiting in line for a shower, etc..