Just a thought, bypass the hottest part of the southwest when you get to some place in west Texas. Maybe jump onto the train in Alpine, TX and take it to someplace in California?
https://www.amtrak.com/content/dam/p...table-0317.pdf
A couple years ago a friend of mine was averaging seven flats a day in the southwest from the thorns he was picking up on the road.
I think it would be neat to ride through Death Valley, but in winter. Keep in mind that if you have a mechanical problem of any kind, if a car driver does not stop to rescue you, that could be pretty serious. I have biked where there was not any retail establishment of any kind for at least 100 miles in any direction, but I had an extremely reliable bike and the tools and knowledge to fix almost anything on it. Plus, I could have walked for days out of there if I had to because the weather was not something that would kill you in a day.
Someone above mentioned how hot the pavement can get in the sun in Death Valley, I have no idea what that will do to your tires and tubes.