Here is what I like for a small board
its only 16.5" wide and 5"10. I have a 6.0 that is 18" - size is similar to a traditional competition shortboard for surfing and its a good light wind board but way to big when it gets to 20k.
I shaped this board and others. Long story short, the subject of rocker is complex and there are plenty of guys who make boards that do not even understand it. A kiteboard may have 2" of tail rocker the breaks from the mid point. It will be fast but a poor turing board (it will turn like a jon boat). you can have 2" of tail the breaks over the last 18" -- much like a traditional surfboard - it will turn very well, but may bog down and stall at the end of a turn. Find the guy who knows (shaper, not rider) and tell them what you want the board to do. Turst them to make a board that does that.
Cheers
Shiner