You might want to cut the back out of it and applique it to another piece of fabric. Then use the fabric in the back for other squares around the outside of the shirt. You will probably never match the fabric anyway. Leave the back yoke to cover the neck opening and enought to turn under the sides. You could do the sleeves too, if you needed more fabric. I think it sound like a cute idea. Stitch the front opening shut so it doesn't come open accidentally.