Piecing a Backing

I was getting ready to pin Alex's winter quilt all together the other night and then realized that 44" fabric is not quite wide enough for the quilt.

The quilt is 50x60ish, so if I cut two pieces 60 inches (or 70 inches long to make sure I have enough) then I'd end up with an 88 inch wide backing and that's excessive. Seems a waste to make a backing that big and then end up having to cut it down a lot at the end.