At Harbor Freight they have carbon stipping discs for the angle grinder. It takes the paint off like nothing and does not damage the panels at all. it actually polishes the metal so don't forget to hit with some 80 grit to get the mechanical bond back.
I also have the drum sander version from HF also and it strips paint like nothing!!
https://www.harborfreight.com/4-12-in-non-woven-paint-and-strip-abrasive-wheel-70419.html
great job on the progress!