I've achieved the desired boyish figure.
However, there are still problems with the back.
That's not pretty. The back princess seams look better closer together, and the added length at the bottom edge helps, but those wrinkles! I can't kid myself and say they will disappear when the corselet is pulled down by the garters. That should help, as will functioning shoulder straps,and fabric heavier that quilter's cotton, but I think what really need to do is shave a bit off the seam between the waist and shoulder blade. If I can get that area to fit as snugly as the front then maybe the top won't sag downward. I don't know. Fitting oneself is difficult.