Linda, yes letting the brakes cool is truly the right move given the astronomical heat, I will follow your advice.
Since the seals blew a few years ago they have been changed, bearing repacked, diff fluid swapped. I am "good to go" or as good as I will get..
My motor stays impressively cool, the cooling system keeps coolant filled to the top for a very long time and never overheats into the overflow( I use to lose a little, turns out it was a crack in the seal of the radiator cap gasket)
No, I am unloading as much as I can in the next hour in my brother's garage in Huntington Beach to try to (feebly or not) reduce weight and reduce brake temperature. I get terrible heat fade from the front rotors that ought to be resurfaced (or rather, go thru with the fully toyorv brake upgrade of 4 runner master cyclinder[one thing I've done] 2 runner/tacoma calipers and rotors).
I have no ac (well shore AC powered oem wall mount ac works great!) but the truck ac needs a recharge, Fan works, heater/heater core works, I typically use the windows, at least on the 5 I will keep moving.
Also, I plan on driving thru the night, I hate the psycho suicidal car drivers and rather drive with the trucks, and rather drive one simple route than one mountain pass (ugh) then the squiggly routes, although yes you are all right, the 101 will be much much cooler, even down in Seal Beach it's not even that hot probably 78.
May I ask why the consensus among you longtime toyota rv owners is to take the 101 over the 5? Is it purely heat related? Or is it 299 related, the pass I have to traverse?
Thanks again for the guidance!