From the looks of the photos, it could be done.
My brother-in-law has built trail through solid rock walls, without
blasting. He has a trail machine and he used the backhoe portion, I
think. He has built trails around here with it. Someone with a
trail machine could do it, I'm sure. Some of that terrain in the photos
looks like it could be widened with a Pulaski, McLeod, and/or a
pick. Lots of distance, I agree, but I understand the California Loop
was created with a trail machine, so where is it now when it is
needed?
One of these days, someone is going to be killed, and
I think the trail should be widened before that happens.
I know I would be terrified to even ride it at
all, but then I'm very frightened of drop-offs.