Thanks for the advice BJ.
Here's the basic design -
Shell material: green canvas or black vinyl (green canvas shown in diagram for clarity - colour sucks)
Window material: clear marine vinyl with zipper closure (window is more rounded than in diagram)
Hinge: Stock 40-series door hinge - each attaches with three bolts that go through the shell and into captive nuts welded to the hinge mounts.
Latch: stock 40 series door latch
Door Handle: not specified - need to see what works.
Top closure: prickly side velcro stitched to shell - just to stop it flapping around at the top. Fluffy side velcro is stitched to soft top.
Frame: 10mm round bar welded (shown as grey in diagram)
Anti-intrustion and hinge/latch mounts: welded flat bar (shown as black in diagram) - thickness and materials depends on ADRs
Top of lower half of door frame: flat aluminium bar (not shown). This is bolted to door frame and holes are drilled for tabs of upper half of door. Depending on how it works, might add short sections of 10 or 10.5mm ID tube to receive tabs.
Tabs: 10mm round bar with holes drilled for locking pins.
Weather seal: (not shown) from Clark rubber and glued on with sikaflex or maybe seamgrip - need to see what works.
Diagrams:
Exterior:
Interior - showing frame and internals
And a quick photochop showing the doors and a notional canvas soft top
Possible design adjustments - add an aluminium or sheet metal skin with canvas or vinyl covering.
Can anyone see any major issues with the design apart from flapping from the shell material?