I am in the process of setting one up now for storage. To help cut the high temps, I am doing the following....
* painting a light color
* putting a 12' shed roof going off the side that gets the most (morning) sun
* placed it on the east side of my shop building, so it's shaded in the later afternoon
* putting a 12v exhaust fan on one end powered by a solar panel (no battery, only runs in sun)
If I was going to use it as a working shop, I'd cut a door or large window in the end opposite the doors so could get good air flow with a big fan.
To help combat the moisture, i have it 8" off the ground on the uphill side, 20-22" on the downhill. If you sit it flat on the ground, you'll get moisture vapor up thru the floor.