Intresteng but are you wanting to plane or plod or wave ride.
Guessing ...... achieving both is the goal ,but hey in the early days on the west coast of SA the old school masters Paul Grevelle and Sunny in the 80s and 90s only ever used a 4.0m in 5 to 10 knots but had floaty chuncky 8 foot thrusters boards called wave pigs ........they shreaded it up in 2 to 10 foot.
Over size sails on a small sinkyboard defeats the purpose ! Never be shy of volume ........... u just gotta get the rocker line and rails right and the dragon will be slayed.
I GOT 2 wave boards a total floater carries my biggest sail 5.6 for 5 knot up and a semi but floater generally 4 my 5.0m............. but it will carry my 5.6 not the sweets combination ie big sail on smaller board
Any way / many occasions ill take the floater out in 6, 8,10 foot plus and get the same performance on it as my slightly refined semi but floating smaller board .
The only factor effecting its overall performence is its ability to handle chop. The boards are shaped pritty simmilar ,but its the volume that allows gusty light conditions to be handled with easy.
In fact i shaped the floater, with one thing in mind....... i wanted to be the last one on the water and watch da kites fall out of the sky around me .