I've been about that high up and hammering on some misplaced concrete, but not dangling from a set of chains. F that.
We loaded a Terex similar to this one about 3/4 full and level with dirt.
The teamster drove it down into the diversion channel, down a grade so steep he was out of brake air pressure about 25% of the way down.
No worries, I had one of these in front of him and backed him down there, includiing around a switchback.
Then we rigged up the backhoe like this one with real rigging, not some half assed chains:
Picked it up with one of these sitting way above us on the middle road.
Then I climbed a ladder and set the backhoe where I wanted it, unrigged it, set the outriggers, and directed the teamster to back me up till I could reach the concrete.
Then I raked off about 8" across a whole panel pour measuring 16' x 24' that was poured there in error.