I was just looking at an old LA sectional--looks like a nice airport just NE of Joshua Tree. It's called Twentynine Palms MCAGCC. I've heard they're really friendly to transients.
Seriously, there's several private strips shown near there, including three clustered together about 20 miles NW of Joshua Tree. About halfway between Lucerne Valley & the MCAGCC, right along what must be Hwy 247. They're right in the middle of a big dry lake area. Unfortunately, they are all marked R (invitation only).
Seems like there oughta be plenty of cool places to land in that part of the country. Just be careful around the restricted areas, they don't call that Marine Base the "air-ground combat center" for nothing!
Eric