When I am referring to floating, you don't need to physically change the difference in height between you and your partner to be under them. You want to redirect their force down to make your partner go up. I discussed part of one way to do this with my shoulder video post.
I think your confusing imagery with what is actually happening. If you are not actually below them, in some way, you are not horizontally more stable then they are. Nature rule Hunter san, not mine
. When you are feeling with your intent, what you are actually doing is finding a "sticking" point in their body, then you drive under that sticking point, from a lower position. Because their whole body is connected, once you find a spot to raise them up, their feet will go as well.