Here is it installed.
I used 1/4 recycled lexan. Rubber 3/16" Epdm washers between the lexan and hatch as spacer and stress reducer. A good bead of sealant adhesive. SS fender washers on the outside of the lexan to reduce point stress again
The stainless screws are left to long so that I can put a thin piece of lexan on the inside as to make it double pane.
The only complication is to leave enough flat material to mount the window to.