Another option that is more money is just go to an industrial coating manufactures. The have a ability to dip the material and when I priced my AS they thought it would be $350-400 to drop off *all* the aluminum trim pieces and strip them down to bare aluminum and they could do upto 15-16 foot lenghts.
If you are just doing a few pieces, oven cleaner will do the job, but wear protective gear and do it outside. Also, it works better when it's warmer outside.
For my shower, I'm looking at using some 1.25-1.5" thin aluminum flat stock and just rebend the piece for the shower/countertop. Then all I need to is drill new holes with nice evenly spaced rivets and no more insert either. I thought about using stainless steel but not sure how the coefficient of expansion difference will affect or matter. Might need to try an experiment.
Alternatively I could mount the trim with 3M VHB tape which would provide some 'give' during expansion / contraction... but I may want to remove it sometime. That stuff is scarey sticky.