I gave up on birthing quilts the old fashioned way. I opted for the give me the drugs. :lol: :lol:
I know you have seen the pillow shams that open down the middle in the back. Imagine the pillow sham being the size of your quilt. I make my backing like that with one side overlapping 1/2" and machine stitch it closed to incorporate the seam into the quilting design which is usually straight line quilting on quilts I make like this. It works great for small size quilts or utility quilts. It's easy to smooth the quilt so there is no puckers and excess fabric with an opening down the back.