Alumigrip paint is commonly used for painting aircraft.
...wow. Alumigrip is a legend, and goes back to about 1968 (first post-trial fully developed product aircraft application), developed by US Paint, Bayer (Germany) and Monsanto jointly (Monsanto made hydraulic fluid {Skydrol} that dissolved aircraft paint at that time, so Monsanto, being a global coatings manufacturer, like US Paint, helped out). A very close relative of mine (and an award-winning coatings chemist) who worked for one of the above companies for an astounding 53 years, remembers intimately the US Paint/Bayer/Monsanto venture and 1st Alumigrip aircraft trial (an Douglas DC-9, the 1st DC-9 made, painted in 1964, then delvered to Ozark Air). I inherited the extensive coatings library (thousands of books, and other hitoria) and have just started shelving these early and ancient coatings chemistry industry trade books (it may be one of the largest collection of early trade industrial coatings materials) in our new 45-foot long ceiling to floor library :)
The OP:
IMO, the absolutely best way to proceed here is to use ether TPO (my favorite, for many reasons) or, the EPDM rubber sheet product out there at the moment. Fiberglass, or aluminum, or any advanced coatings will cost you a fortune, and will be an absolute nightmare to maintain (aluminum is very dynamic, and keeping the caulk integrity will be absolutely crucial (Steve's solution of welding the aluminum is the only way to go, if you go the aluminum roof method!)....
Good luck with it,
Silver-
