electrical system weaknesses are always discovered in very high or very low conditions. you gave your system the heat soak treatment test and it failed. all of the things mentioned are possibilities.
i have been stranded when on trips many times in hot weather. so one of the benefits of driving a diesel is that there are no fumes to catch fire at the gas station. when fueling on a trip in hot weather i never shut the car off. ditto on potty stops. when going in for a meal i do shut the car or truck off but i always crack the hood open and leave it halfway open to let out the heat. i figure the wires and hoses can only take so much heat and eventually they will fail, so why give them any more than i have to.

just the observations of a long time traveler.

of course you can do all this and still get stranded, but when it is 100 degrees out why push it? around here it doesnt get that hot very often so if my system is only 97% good why fix it for three or four days a year?

tom w

__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.