I've been messing around with the oil filler door the last two days. It is a simple piece of flat fibreglas, hinged at the top with a piano hinge, and with two wingnut CamLoc fasteners at the bottom corners. It all went well enough, once I shaved away a bit of fibreglas to allow the male part to go deeper into the receptacle. The door is all ready to rivet to the hinge, but I think I'll hold off on that a bit, the hinge pin can't be removed once the hinge is riveted in place - I would need to drill out the rivets if I need to remove teh door for some reason.