Any chance of re-routing your trip? Do the northern portion first then come down to the desert when the monsoons have begun and it cools off?
Siteseeing in the heat we're having will not be fun. Better take an anti-crabby pill! :)
Your biggest concern will be your refrigerator. Definitely try to park so it gets afternoon shade at least.
Have the silver insultation product for your windows. They really help.
Don't try dry camping. You really need air conditioning in this heat. Bring along an extra fan or two to move the air.
Good luck!