My design dilemmas are over. I have gone ahead and shaped the board. After much deliberation I decided that a flat bottom was more appropriate to the board’s needs than concaves. Lots of roll in the nose, flat bottom, lots of vee in the tail section, downturned pinched rails. I think it will go.
Photos here:
http://www2.swaylocks.com/node/1028002?page=203#comment-1451441
Thanks to all for your input.