Window install in thick walled Cargo need help

I just bought a new 12" X 18" 90 degree window with rounded corners along with a trim/clamp ring for 1.25 inch thick walls from Redneck trailers (1.25 inch seems to be the thickest wall for RVs).
My Cargo has 1" walls with 3/4" plywood attached on the inside for total width of wall = 1.75 inches.
No instructions came with the window so was hoping to get some ideas here. I did a search but did not find any detailed info on a Cargo window install with an extra thick wall like mine.
Here is my plan of action so far:
1) Glue ¾â€
My Cargo has 1" walls with 3/4" plywood attached on the inside for total width of wall = 1.75 inches.
No instructions came with the window so was hoping to get some ideas here. I did a search but did not find any detailed info on a Cargo window install with an extra thick wall like mine.
Here is my plan of action so far:
1) Glue ¾â€