Ah, makes sense. I really would be able to find use of a long, black quill seatpost.
Would like to see if you are successful, not that I doubt you at all.
Never heard of a Mecacycle but I do have this Moser badged Rigi. I suspect though that it is for the Mecacycle because from what I can see the seat tube is much longer than on the Moser Rigi and stem pictured is not exactly super leggera.
@HHC exactly! This was designed for a Mecacycle where the seattube is split which allows access from underneath.