We did Big Bend a couple of years ago in April with a fifth wheel. It was over 100 degrees making our stay at the Rio Grande commercial campground a must. They have full hook ups there. There is a much cheeper park service primitive campground at Rio Grande Village as well. Not sure how busy it might be over the holidays. It is a really big park so be prepared to have to break camp and drive your class C to get to things. The best hiking is in the Chios mountains area where access is restricted to around 25 ft as already mentioned. There is one tight switch back going up to Chios that forces that restriction. Once up there it opens up with plenty of parking and a lodge. There is a primitive campground up there as well if your rig fits. Check the NPS web site to be sure. The views are breathtaking. It will be much cooler up there as well. Big Bend is one of the least visited parks because it is so remote. Well worth the trip.