Forgive me, but I still can't envision how this works. Any chance you could make a video or show some pictures?
What I'm trying to picture is a WP/non-breathable fabric (in this case, cuben) filled with down. You can deflate any air in the material via an air pump, in order to pack it up. Likewise, in order to achieve loft, you inflate air into the quilt via an air pump.
Most bags, made of breathable nylon (or other similar material), naturally loft and pack down through passive air permeability.
Your use of cuben allows for a bona fide waterproof quilt that also acts as a vapor barrier while achieving the lowest possible weight. While we cannot add clothing to supplement a bag's rating because of the VB effect, the use of incredibly lightweight shell material (i.e. 0.33 cuben) lets us choose a bag with a lower temperature rating for the same weight.
What did I miss?