I don't do falls (yet), nor am I one to say something can't be done...
But I'm not sure Shoshone Falls will ever be run. For a number of reasons, really. One: putting in would be illegal trespassing, so you'll have to deal with that. Two: It's only "in" a few weeks a year, and the tourists are pretty heavy, so that makes it even harder to run inconspicuously. However, I'm not sure it would be best to run with it is fully "in," but rather, better at moderate to low flows. Three: I'm not sure there's a clean line unless you go far right, which is where the bottom shelf exists.
I grew up in TF, and while I don't know a lot about SF as it relates to dropping in a boat, I've spent enough time there to be amazed as the sheer force of the water when it's in.
Would be amazing to watch happen.