Here is a link to an Airstream forum that might be helpful: http://www.airforums.com/forums/f36/story-...apes-29321.html
I had never heard of using a story stick before. Looking at the pictures and the description makes sense to me. I would think roughing in the basic curve on some sort of stiff board and then getting the final curve using a compass the way Norm Abrams trims cabinets to fit uneven walls would allow you to fine tune the curve on a pattern before transferring it to the plywood.
I've seen several mods on Casitas and Scamps for closet shelves, rear shelves, and new bulkheads where this technique could prevent lots of frustration.
By the way, I forgot -- there was also a different thread on the Airsteam forum for making bulkhead patterns. Here is that link as well.