I have a lot of auger bits. I am considering using them for this purpose, but I will still need extensions. I am drilling 4 and 1/2 feet down from the top plate in this particular rewire, sometimes the blocking is up to six feet down. I drill two 1" holes in the top plate, one for the drill and one to look thru. Then I drill the wall blocking with extensions. I have used the flex bits but they are not so great, hard to control and they don't stay sharp for very long. Sometimes they blow out the side of the plaster wall.
I do a lot of historic homes, where the plaster is best left undisturbed.
