Very interesting stuff, thanks a lot.
About convoys, I think it is important to note that whereas fuel efficiency (cargo.miles / fuel use) plays an important role for long shipping lanes, speed is just as crucial. Faster convoys mean quicker turnaround, less ships in the lane, and less fuel burnt. This makes fast ships like the Kyushus even more efficient than CM/F ratios suggest (and slow boats like the Gozan even worse than they seem).
This said, speed and fuel usage only matter for long lanes (which one would try to minimize anyway). For short trips, transit time (and fuel use) is dominated by loading/unloading costs, which favour small ships over large ones (in general the smaller the ships, the faster they load).
And since a large fraction of resources move over very short lanes (Korea and Hokkaido), I believe the most important decisions at game start revolve around the allocation of the small xAK and large xAKL. Limiting factors, there, seem to be Honshu port handling limits (eg Ominato).
I had considered this (the same as you), just hadn't got around to putting pen to paper and fleshing it out more. I'll definitely include some type of speed/transit time info into the final doc.
Thanks again -