I had a similar situation with a quilt for my daughter, what I did was split the backing in half, cut a 7 inch piece off one end and put a complimenting piece on both sides of the 7 inch. So it looked planned, instead of the pure frustration it was. When my daughter saw it she thought I was trying to make it 2 sided. Told her it was my attempt not to take my frustration out with my rotary cutter.