>>11311887
Unfortunately, I think the easiest solution to her sinking all the way consistently, aside from >>11311907's suggestion is to feed the AI an image where she's already atleast chest-deep. The 5 sec timer is just too quick for a satisfying sinking.
I also used AI img2vid for this kind of stuff, except with 3d asian girls instead of 2d anime girls. Even then, I can't get em to struggle either. Bummer.

But damn, that last paragraph is such a hot fucking scenario.