[jime57]

To take the boattail discussion in a very slightly different direction, does it make sense to construct the boattail in sections? I'm thinking of about three sections, a top, a bottom, and a back, with a clean seam between. This approach potentially has disadvantages, but it also has several advantages:
1. It obviously facilitates the tweaking of the contours of the various sections separately,
2. It allows for the rapid testing of alternate "sectional" ideas, even the total length. The pieces could be ready,
3. It facilitates an essential goal, IMHO, of keeping the road clearance within realistic bounds, while significantly improving performance.

At the end of development, one could simply bond the sections together and lay a final layer of fiberglas over the whole thing.

The risk, it seems to me, is that the improvements in Cd from such an approch might be disappointingly small.