I thinking the same you'd be flying a Muscovy instead of a kite.If it was that easy and quick one should be able to just follow the duck.
Knowing my place and how my ducks are I'm imaging it'd take a very long length and there's no way it wouldn't get tangled up quickly.
Now if I could get her to take to the air to get to her nest it might work. I could follow the string like it was a crashed kite.