How would I find...

The absolute most heat resistant strain available to man?

You would take all the strains that come from hot countries and then check which is the most resistant.

now this is a worthwhile thread/topic, the pat answer is landrace strains from the desert areas
that said, it doesn't give you much of a list
but for genetics that have heat resistance, certainly some afghans are going to be in that category
and those genetics are available from many breeders, but reworked to varying extents
the Real Seed Co. have a good rep for landraces, and very reasonably priced, they do have a Lebanese strain of the hash variety
the breeder Mandala has quite a rep for heat resistant strains, breed outside in Spain i think, and has some landraces too

live and grow in death valley?

Seriously I live in So Cen valley
normal summer temps here are 100+ low humid tho

I water almost daily (soil is homemade so I know what it requires) I am able to water daily and check on it daily.. as any good grower will do..

1 day away from them = a dead plant at times..

I love the bubba kush but all my others from blue dream to trainwreck did fine last year.

Look @ some African strains. Moroccan etc. Dry, hot countries near the equator.