Interesting, but a bit confused about one thing, WHY ?
When you go downwind your speed diminishes, thus much easier to ride going very deep, and this is what you do if you feel you go too fast downwind, but still want to go downwind (home ?) as good as possible.
In fact, when you do this, you can, might even have to, sinus or loop the kite, as otherwise it will have no power and you might stall the hydrofoil because of lack of speed
If you go halfwind or on a broad reach, THEN you will get in trouble easy, if not used to it - indeed.
But you can easily avoid this by going deeper till the kitepower and speed goes "away"
Or, fly the kite up higher, slowly, to decrease speed, if on a reach going too fast for your liking.
(PS: One more reason why NOT to use non depower C kites that sits deep, as then this easy step becomes difficult almost impossible for some