I made gaskets out of foam tape.
I will just be using a thin bead of sealer next time.
The gaskets take up valuable space needed to get the lens to fit.
I found if you tape up a border on the underside of the cover about the width of the flange it lives on in the body, sand it with 280 wet and dry, then paint the border (on the underside) with black acrylic lacquer.
It looks good an hides the sealer line.
I don't have a pic of covers but windows are the same.
Most just use s/steel screws, it is plastic.
My body is aluminium, I used screw grommet blocks you need to file a square hole then they push in.
If you strip it pop it out and push in a new one.
Use the ones with a flush flange.
link
JNS Australia Pty Ltd - Product catalogue - Screw Grommets
I think the glass body will be to thick, it will most likely end up a self tapper.
Hope this helps
Jim