Instead of doing the quilt like a jelly roll race, think of it as just a quilt made up of 2" finished strips. Let's say you want the width to be 90". Start out by sewing all your strips end to end (like in the jelly roll race) but off 90" of both ends, sew these together, then continue chopping off 90" from both ends and adding to the quilt. It will have the look of a race quilt, but you won't be confined to the dimensions of a race quilt. Of course you will first have to figure out how many strips you need, but the beauty of it is that if you didn't figure on enough you can always cut more and start adding them to the quilt. Your son will never know the difference between this and a race quilt, and neither will anyone else unless they are aware of the dimensions that develop as you make a race quilt.