You don't have to camp in a campground in DV.
It's a vast place and there are plenty of places where drycamping is allowed. There are some rules for drycamping in the boondocks .... just ask a ranger what the rules are or search for them on the WEB.
We camped in our Class C motorhome in a flat area just off a 4X4 road out in the middle of nowhere in DV. What a great experence sitting out in that beauty eating hot buttered popcorn away from the crowds!
Here's a .pdf link to the backcountry camping rules for Death Valley:
https://www.nps.gov/deva/planyourvisit/upload/Backcountry-Camping-2017.pdf