This question is not about personal preferences between hammocks and tents/ground pads.

For hammock hangers on the forum-- can one hang successfully on any combination of rock crevices/tree; trees alone; or rock crevices alone at the most common overnight locations between Onion Valley and South Lake? Thanks.

Warren, I'm not a hammock user myself, but in my opinion, it would be quite a hassle to try to find a camping spot where a hammock would be accommodated.

As for rock crevices: Most "common" overnight places don't have boulders and rocks large enough to use for hammock hanging.

While a few common places have enough trees, I just wouldn't count on finding them every place I wanted to camp, as you would need to try to camp below the tree line.

However, I just did a search on the Facebook "John Muir Trail" group and found this:
  Has anybody hiked the entire trail using a hammock?,
and several reported they were able to hike the entire trail. I suggest you read that thread.

Thanks Steve...I'll read the link you provided.