Joe, very creative as always. I had similar thoughts to Nick - material forward, eyes slightly back "inside". Also, depending on the size of the fly, maybe a more mobile material top & bottom for smaller patterns?
The idea of a fly which incorporates "empty space" seems sound - since camouflage in the naturals has the same effect. As always, the fish will be the final judge but I would fish those with confidence.
I think they may work very well "dead drop" on busting tunoids