The best way to handle desert heat is higher elevations! It is cooler up there!
Or travel at night, that is what my great aunt did when they came out to California in 1942. No air conditioning in those days, and the cars overheat on a long drive when it is over 85F outside!
Reflex insulation is on my south side windows while driving on a hot day. I also will run the rooftop A/C and generator, in addition to the dash air when not climbing a mountain grade. Mountain grades, and I normally turn off the dash air, as it prewarms the air into the radiator, as well as add an additional 5-8 HP load to the engine.
Good luck,
Fred.
