Randahl, what line length do you use when its light ?
Its just, even on a small board, I think you can loop the kite to get on a plane, and pump the board up on the plane actively with your feet.
Then you should be able to start with one size smaller, and get going without being overpowered
You probably know all this, would just be sure
Current or not does not change this balance between starting power needed versus foiling depower needed though
My experiences are, that a big kite (maybe like the C 14.5) is awesome in absolute marginal conditions yes, and works perfect.
But you could have one only slightly smaller, because just a tad more wind, and you can not use the 14.5 that well (at least this is my experience although with a Dyno 13m2)
My point is, that diving and looping the kite, and pumping with your legs, are all essential for getting up foiling, especially in light wind, if you dont want to feel overpowered when up
And a tad smaller kite can IMO generate the same power when looped.
For racing it is a different matter though, and bigger sizes are used