I salute you my man for helping those countries out!
“The temp gets to about 140 degrees F. I bought a pair of Asolo FSN 95 GTX boots and now I'm looking for socks. Can anyone please recommend a sock for this extreme temp?”
Not cotton. They get sweaty wet and stay wet. And then the fungus grows and stays.
I would suggest thin coolmax socks. There are several brands that use this material. It will probably only last a year, but at least the feet perform better.
I use black socks from JCPenney. In bulk, I pay about $2/pair. I can’t find a web example but they’re similar to this but black:
(ouch, long link).
However, GTX boots and 140F do not get along at all. I’m suffocating just thinking about it. There’s a reason a lot of the locals wear sandals around there.
Personally, I would wear sandals w/ socks. The socks wick the sweat quickly away (especially the underside) and minimizes sand burns.
Good luck on your feet endeavor,