Leaking window in pole building, wanting to insulate

[bearskinner]

I removed the only window in my pole building ( metal over 2x6's flush girts no plywood) that the PO had installed with j trim, no window framing, just screwed into the 2x6's. No sealer, and on the weather side of the building. We get lots of snow and rain. I was thinking if I reinstall the window under the metal, that is cut a little too big for the window, it would be impossible to replace the window if I frame up the inside and spray foam the interior.
Question..... Can the window frame be built out a little so the surface mount window can be mounted outside the metal in case it ever needed to be replaced? Possibly build a small eyebrow over the window?
If I install the window between the interior wood framing and the outer metal, and seal it properly, once the interior is framed and foamed, how could you ever get to the window to replace it?

 

[Kaizen]

a surface mount will have a nailing flange on it several inches wide. that won't cover the larger hole cut out? only reason to build out the frame is to make sure it has adequate support to the 2x's. no way i'd install it on the inside. just asking for it to fail

 

[bearskinner]

Every installation I have seen shows the flanged window mounted between the wooden window frame and metal siding. Once the spray foam insulation and interior framing is installed, how could you ever replace the window?