in the river. I realize California is in a multi-year drought, but I have a hard time imagining no water at all in the river.

They didn't have anyone checking permits back then, but if there is someone now, the bottom of the cables send like the logical place to do it.

We did an overnight pack back trip, so I don't have a good time estimate for a single day hike. But it is 16 miles, and you gain several thousand feet (I don't remember exactly, but I'm sure you already know), so an average of 1.5 miles per hour or so is probably not far off (depending on the pace of the slowest hiker in your group). And your have to consider time spent at the top, too.