I quilt on my Bernina and I want the least numbers of seams allowance on my backing so I wouldn't use any small 2" squares. You are going to have a hard time lining up the back with the front. I had one client that gave me a backing the same size of her queen size quilt. It took me hours to get them lined up. I did this for a backing of a charity quilt because I wanted to use up the two extra squares.