Given that primitive campsites within the park fill up months in advance, Stillwell RV Park offers overflow campsites just beyond Big Bend boundaries. We booked a lot for cheap on the Stillwell website. The small shop offers basic snacks, cold drinks, and camping supplies. Just be sure to get there early. The shop closes at 6, and if you're counting on a cold Gatorade at the end of a hot day, like we were, you may be out of luck if you arrive late.