Like I said, I tried a large number of options and the paint removal tool I linked is the best method I found. It won't damage or warp the panels, and makes a good surface/tooth for the epoxy primer. It is also quite inexpensive. You can get a similar paint removal disc that fits a drill, and possibly fits your angle grinder, but this won't be the same (although the drill mounted disc is helpful as an adjunct for tighter areas).
The paint removal tool turns at a lower rpm than most circular grinders/polishers/sanders and this is optimal for paint removal without overheating the metal.
Fred