If you do pass though Death Valley, aim to camp at the Wildrose or Thorndike campgrounds. (There is another, higher, site, Mahogany Flat, located at the end of a rather rough road - not healthy RV territory.) These campgrounds are located in the mountains just west of the valley and are significantly cooler than the valley floor. It is not unusual for the night time LOW temperature on the floor of DV to be above 38C/100F.
A while back I read an interesting post regarding the recent discovery of some (very dead) long-lost German Tourists that had visited DV in the summer. They had attempted to drive an extremely rugged jeep road across the middle of nowhere ... in a small RV van. Tires shredded, out of water, they attempted to hike out. They didn't make it more than a few miles.... Anyway, the point made in the forum was this: The word 'park' has an entirely different meaning here in the US than in Europe. Europeans tend to see the phrase "National Park," and think of a 'tame' facility, a zoo or arboretum perhaps. In reality, dozens of people die each year in our 'Parks' The whole idea behind the National Park System is to maintain the land and wildlife in as wild and natural a condition as possible. Consider the Grand Canyon. There may be guard rails at the more popular tourist sites, but once you leave these areas, you are on your own. People constantly underestimate the summer heat, the height of the cliffs, the slickness of a trail following a summer thunderstorm, etc. Occasionally this overconfidence kills them. I don't mean to put you off visiting, but DO be aware that you are entering potentially dangerous areas. Do some research, be prepared, and use common sense - you'll be fine!