U R 100% correct, but I think us heavy guys can improve acclleration enough to give the light weights a good race, so I am hoping a pro has the answer.
1. Mast foot - U and I are definately correct in marginal conditions with a 100kg at the back the rear sinks and the board planes at the wrong angle so thats not the answer.
2. When I lost 5 kg in weight during the early summer, the board definately plane for longer and quicker in marginal conditions. My weight was 95kg. That weight will plane with a 10.5 in 10 knots of wind if u keep out of the straps, raise the boom to chin height and hang. I have to keep on my toes to allow the board to rise out of the water. At 100kg I cant get the board to do that anymore.
3. I am wondering if in marginal conditions u use a soft 70cm fin run off downwind (easier to do with a soft fin) then hopefully come back up on the plane to winward.
There must be other tricks the pro's use because they all seem to accelerate quick on the videos!