I sprayed the front of our (now sold) aluminum sided fifth wheel with Rustoleum white after I ruined the paint with TSP.
I'm not a pro at all and it turned out and lasted very well.
It never peeled and looked great right up to the day the new owner towed it off.
*btw
Acetone, MEK or TSP will prep the old surface without much sanding.
Full strength TSP can take the old paint on aluminum right down to bare metal.
Found this out by accident LOL...