I can feel my head expanding (yuck). One figure in your tech data jumps out... 6 ft away is too far for your light source to get the effect you want. Bring it as close as you can without entering the frame.(posted 8842 days ago)The larger your source, the softer it's light. Moving the box away is the same as using a smaller box. I think Ellis (on photonet) quotes a formula about the distance of the subject from the box not exceeding the diagonal of the box (or something like that) for the softest light. Use additional scrims on the lower part of the vertical box to keep detail in the white blanket.
I'm glad you found my observations useful. Let's see the next take... t