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Wise of you to consult our group before entering a tug-of-war match.
(you'd loose).

The interior panel folds 90° under the window then again 90° up. Joins the exterior panel and rub rail. All three are riveted together as one. (Older models are have the lip inside, but still joined to the exterior.)

Cut the wall steel (inch or more) below the window. Pry/peel away from the sealant & remove.

Walls easier than floors. Ceiling absolute easiest. (IC uses 'Pozidriv' screws & sealant).
Resealing windows was simple, cheap and provided the most gains. An old lady with no construction experience resealed ours.

Are you familiar with the one-and-half inch (convection) gap over the top of each window frame?
For more details, please skim through my
Interior Demo & Mod Albulm (cracks, codes & cheats, hidden in the photo descriptions)