Thanks for the great ideas. OK, two doors, put on canvas first, SS piano or knuckle hinged applied on top of canvas (might get a mortise underneath canvas to work with depression passing thru - will test), no center post needed, Toggle bolts to hold inside door, some swivel lever action lock to hold outside door, inside positive stops with gasket are ok, including one on lock side of toggle closed door.
"Garage" Lock perhaps like this one that can compress as it turns

What do you call that outside edge molding, GPW ? gotta know what to look/ask for