Replacing Truck Cap Windows

I am building a Camper in my truck using an aluminum cap.
I want to replace the 18in solid glass windows on the side of the cap (near the rear) with ones that open to allow air flow without opening the larger side doors.
the cap is an ARE who I called and they told me they don’t make their awning windows in that size anymore.

I found a window from Unicover of the same dimensions. Would I be able to remove the screws holding the window in and just place the new window in the same hole? Or are these windows held with something in the top underneath the gasket bringing the top aluminum skin and side aluminum skin together?

What would be the best way to replace these windows?

Thanks!

Just take it apart and see if and how it fits.

Sometimes you have to take screwdriver in hand and have at it.