Gerry, cut out your door where you want, making sure there is about 2 inches around the cut on the inside that is just the foam stuff with no mounts or other part intrusions, use the piece of Glass that you cut out as the door.
Be very careful when you cut it so the edges are straight
Cover the inside of the door with saran wrap and tape it back
into place on the outside.
On the inside cut back the foam stuff about 2 inches and put
a couple of layers of fibreglass covering the cut back and
about 2 inches onto the saran as well.( Rough up the old glass
surface for good adhesion.)
Remove the door (glass won't stick to saran) and cut the glass
you installed back to make a nice lip and paint
Add a bit of gasket and hinge where ever is best , install
a small lock like in a tool box. DONE!