just a note: it works without the back opening!

I made a 2+2 blouse with some vintage fabric, a pretty floral-print eyelet. There was not enough fabric width-wise to have the eyelet run in the same direction front and back; after some fiddling it occurred to me to see if I could eliminate the back opening and cut the back out as one piece, and just make the front slit/neckline a little bigger to go over dd's head. It totally worked! I added about 1 1/2 inches for a size 6, which was perfect and not too low/breezy...