Seems to me all the best light winds kites are big kites 17m +,the idea being having a large wing catches more wind
But the problem is swinging and looping a big kite is difficult,they are slow

I can fly my 7m kite in no wind, Ive done it !

Need someone to launch the kite,or throw the kite
then I just swing the kite back and forth,looping it and agressively moving it generating speed and power to keep it flying
its not that hard

If you filled the leading edge and struts with helium that might help too
Just need to make a supa powerful smallish kite

Probably need to reinvent the board too,maybe a remake of one of those foil boards

Just imagine cruising around the ocean on a oily smooth windless day,looping and throwing the kite back and forth,going where ever you wanted
Going upwind would not be a problem as there is no wind

Be a good workout too