A lot of information here.

http://www.bigbendchat.com/por...dex.php?action=forum

You can make reservations for BBNP but only within 24 hours of the time you plan on camping. I don't have the link for the website but ask for it on Big Bend Chat and they can help you.

Research the state park thoroughly before you decide to camp there, it's not for the faint of heart. Park HQ is an hour off pavement on a dirt "road". Bring everything with you as the only thing available once you get in the park is water from a hydrant and sometimes ice at the park HQ. There is no cell service, I always take a sat phone just in case.

Next week the daytime temps will be at least 100 with next Friday's high being 110. Once you determine the amount of water you will need add two gallons. People have died in both parks because they came unprepared.

If I find the link to the reservations site I'll post it.

Here is the link, http://75.41.147.131/permits/welcome.php

Let me clarify the reservation statement. You are not actually reserving a campsite, you are reserving a spot in the permit queue, maybe. I've used it 10-12 times with maybe a 75% success rate but this time of year you should be able to get something at the park HQ. Just be aware that during the busy season people have driven down to find no campsites were available.

I just saw your comment about an RV, don't attempt the state park with an RV or a trailer. The first time I went down I drove an AWD Honda CRV and it got a bit suspect in some spots.

Alpine79830 is talking about Big Bend Ranch State Park in his comments above. Davis Mountains State Park is ok for RVs and standard clearance vehicles, and the temperatures there will be more moderate. Carry plenty of water in your vehicle, nonetheless.