When I make quilts this way I make the back in 2 pieces (even if it is all one fabric) and leave an area in the center of the seam that is back stitched a few stitches on both ends of about 12 inches of large, basting stitches that will be easy to remove. I press the seam to one side and layer up the quilt and stitch all around the 4 sides. I open the seam in the center of the seam on the back and turn the quilt. I close the seam on the back by hand and I never have to deal with that edge on the out edge that is nearly impossible to turn and stitch so it doesn't show.