A latch on the fuse - Hm-m. It'll simplify the latch compared with the prototype - I do have ?'s
Will the door still be hinged at front? If so, does that put the handle aft of the rear edge of the door or where? Will that be easy to reach?
Assume the 'window' is still to hinge along the upper edge, and open 1st close last and be able to fasten to u/s of wing to maintain option of 'open air' flying.
Do you have optional/alternate method of fabrication the frames? Very light steel welded, maybe fabric skin.
How about a drop-in door with no hinges or latch, kinda like a sailboat hatch - just drop into slots with maybe a tethered cotter for security. They (sailboat) usually have slight taper to hatch and frame so you only need to lift them a couple of inches to remove. Pretty safe too, as the door is 'trapped' on 3 edges.