I was originally planning on cheating to mark out the bottom skin by laying the fuselage directly on top of the sheet. But due to a lack of space and worrying about damaging the skin with the tail skid I dredged out my high school maths trigonmetry skills and marked it as per the plans. I've still got a grin from laying the skin on and it fits absolutely perfectly, no trimming or adjusting. The same happened with the top skins, it just went together easy. All that worry for nothing!