I made many trips to the Mojave when I lived down south. I would love to join you but, it is a long haul for me now (from the SF bay area). It is usually getting pretty hot already by early May and by late May it is usually too hot for most people's taste. I've never been in June - but assume it would not be pleasant and extrodinary measures would need to be taken to protect one's film and equipment during the day.
The wild flowers should be stunning this year. They would, I suspect already be near or past their peak however.