Ed, somehow I missed this reply. Your post is incredibly helpful. Thank you.
Our garage was an open three-car carport. Two cars got stolen (~1995?) and Mom/Dad decided to close it in. Our handyman at the time built the garage. It is a flat roof (~8ft high), zero insulation. The metal garage doors (a two-car door and a one-car door...the one-car space is where the platform is) face due east. Zero shade throughout the entire day. The roof and any walls that aren't from the house are simply plywood with the hardyboard on the outside. I'm in Tampa. Oh yeah, dryer exhaust is in the garage (no solution to this), and there's a leak somewhere that lets water in right where the patform is when it rains hard. Plan is to make a french drain to solve this issue.
There is no fixing the heat issue, I just have to manage it the best I can. That humidifier is a great start. I've got to get a fan or some cooling unit of some kind. It is almost unbearable if I miss my workout in the morning and I have to train any time after 10am. I have to open the doors (both garage doors and the man-door to the backyard) when I train to get airflow. Getting airflow is MUCH more important to me than temperature, and once I buy a fan, that problem will be greatly alleviated. I may get a portable AC unit, but I don't think that solves the airflow issue like this LASKO fan would.
LINK:
Amazon.com
I've thought that putting some type of spray/foam insulation on the door may help, but have not pursued at all. I cannot think of a shade solution for the roof either.
It was built to protect the cars, nothing else. Mom and dad never would have imagined I'd be lifting in there 30 years later.