Flattening This Cylinder Without Losing 1-1/4" Off Circumference?

I'm looking to flatten this tube without losing a significant amount off the circumference of the original outer diameter, which is approximately 40". I've applied the usual method of making a small incision and then putting in a bend and flattening the object, but this results in a sheet length of 38-25/32" which is far more than I would like. I don't have much experience using the sheet metal features of Solidworks so any help would be greatly appreciated. Thank you!

SolidworksSheet Metal