Reply by William

Can you screw into the metal?
If you can, how about ripping 2×4s in half, stripping it out and hanging exterior grade plywood?
I would say sheet rock, but you have stated a condensation problem, which would probably destroy the sheet rock in short order.
Anyway, the ex-ply could be painted a bright white color that would reflect light real well, which for me (lighting) is always another issue to contend with.

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