Calling John Crocker! Here, finally, is the start of the framing of a wing using your spar-less diamond airfoil concept. Mine's not really spar-less, as you'll note, is carries a 3/4" tall thin spar in the interior of the wing.
The concept as I saw (and see) it is: A nominally diamond airfoil, extra thick, no surface spars to allow the covering to sag significantly between the ribs--point being, it will assume a more typical curved airfoil in those spaces. The ribs may even act as wing fences to control tip vortices, etc. So you have the best of both worlds: A wing that nearly falls together, any flat surfaces serves as a "jig", yet good lift as from a curved airfoil. The shape of the intermediate airfoil (at the sags) could be controlled by moving the high point of the diamond, more experimenting is needed on that.
The wing is being built on the planform of my new Rumbler (pictured below in bones), except I will probably leave off the half-ribs to allow the full sag of the covering material.
Come Spring, I'll be making some flight reports. So far I must say this is the easiest framing-up I've ever done. Didn't even use any pins, the ribs just sat right down on the TE.
Thanks for the idea, John!
--Ray