A medival armor company, www.steel-mastery.com is offering me a custom gambeson with a leather outer shell, a linen inner lining and 6 layers of internal cotton padding with leather straps and buckles for fastening.

Since I come from a hot an humid climate where sparring bouts frequently produce sweat drenched gambesons and even sweat stained outer armor, how would you guys suggest that I clean and maintain this gambeson so that it does not smell over time or become itchy when I wear it?

I have previouly sent gambesons without any leather components to the be dry cleaned w/o any problems but is it possible to do this with this leather component gambeson?

Leather wears down quite fast it washed often. Use a regular cotton/linen gambeson instead. They always get nasty, even from one use. Most I know don't really wash them at all...

Turn it inside out and let the sun light dry it.

I would not suggest using leather. Use cotton or, even better, linen, with stuffing made of some natural organic material. Such gambeson would transfer sweat to the outsige and will cool you down as the water evaporates. Leather is not very good at transfering water, so you will be cooked in your own sweat. Also the leather may soon become brittle because of salts in the sweat. Oh, and about cleaning your gambeson... I usually simply hand-wash mine about once a year. It does not take it that long to dry if the gambeson is made of right material.

Strange. My body temperature is slightly higher than normal too, but I don't sweat much compared to other people I train with. Are you sure that excessive sweating is linked to your body temperature?
Regarding the OT, David has the best solution. Turn it inside out and let it hang in the sun.

The Scots were know to have leather shells on their cotuns.
It most likely would have been stag skin for the outer shell.
This was" the" stand alone armour of the Scottish mercenary class of the era.

Cheers,

DT