As you are aware, the low end has to do with the power of the wave, making you overtake the speed the kite can go in light winds, making the kite fall from the sky. I wonder if instead of using a kite, but using a large wing, would get get you out wave riding in down to 7 k. Gong has a 9M Super Power wing coming out, which for a 65-85 kg rider has a posted wind range of 7-13 k. A wing has the advantage of over kite, as once you are on a wave, you don't have to worry about outrunning it, or it falling out of the sky. I am curious as to the light wind performance of wings compared to kites. I would think that for light winds, you would want to use the largest of hydrofoils.
https://www.youtube.com/watch?v=bby23j4S4Io
https://www.youtube.com/watch?v=wLmKTGs043c