The 21st will be an attempt on the required competition altitude, minus ballast/passengers. Unfortunately, you can't fly there unless you plan on spending over a week, as the airport will be closed to unscheduled aircraft for several days before and after the launch (due to overwhelming public interest).
However, if you've got a private plane and for some unexpected reason had to land, heh, there are DOZENS of former airfields and airports very close. There's Mojave itself, built around the previous airport - the main streets are actually former runways and taxi strips. There's the prior CAP base at Silver Lake (yep, that one), there's Cuddleback Lake Airforce Range (the old landing site of the X15s), Baker field, Myer field... both Mojave and Edwards AFB monitor the emergency civil frequencies in that locale.
For an easy in, Bakersfield isn't so far away, along with the Meadows Field (BFL) airport with domestic scheduled flights daily, car rental, and all the trimmings. Using the BFL code you can get the prices easily, but it won't be cheap to book this close up ($500+).
Yeah, I thought about it.