Had cooled seats on all my last 3 recently purchased cars (except my volt).
I was not that impressed with the seat cooling on either car (Mercedes, Porsche, Cadillac), although it did help slightly.
Somehow the Volt w/ its perf leather in light gray, stays similarly cool.
I think the people, who said the seat material and foam design is more relevant, are right on.
However, pre-cooling is not the answer, as that is irrelevant on a long trip.
I also found proper window tinting to be greatly effective combined with closing the sunroof.
Therefore, I worry greatly about Tesla's glass roof, that has no inside cover to close.
I never sat in Tesla seats, so I defer to those here, to let us know if Teslas seat design breathes properly or not.
I have had some older cars with bad leather seats that don't breathe properly and sweat up clothing and it sucks, so I would appreciate due warning, if that is the case for a Tesla.