dM: I am not so worried about the west side of Whitney. PCT hikers have been doing it for a couple of weeks and it is really melting fast. The chute from trail Crest is easy and soft if early enough, so I would not even be sweating the 97, especially if you decide to pick up axes. We are carrying them if only to do the Trail Crest glissade.
If necessary, however, Cottonwood might be better than Army: its only 11200, and army I think has way more snow. New Army I think still has a hairy cornice.
Lots of beta
here on HST up to K gap, nothing mentioning the waterfall/crossing specifically, but a call to SEKI wilderness office might be in order.
Best wishes on your trip, and I will post what I can up to the 9th.
