Nice quilt...I love your color choices!
Eddie has a closeup picture of how he quilted his...it shows what some of the others were trying to describe.
http://www.quiltingboard.com/t-35462-1.htm
If I understand correctly, you want to add the extra strips to the back and wonder how they will look once quilted. Is that what you are asking? If so, I wouldn't worry about matching the quilting on the backside. It would be nearly impossible to get them to line up exactly as on the front. I frequently add strips either solid or pieced to the back and don't even consider them when quilting the front. They always look fine. :)