I had about 8 really nice looking rope flies tied and I couldn't get them to tangle in them they would eat the crap out of them and when I would put tension on it... no fishy. Nathan fished the leech all day and I eventuallu switched to one myself but still couldn't get them hooked up. Just remember to let them eat, but not easily or they will smell the fly and not eat it. They can be a bit on the tricky side.
When I was a kid near Galveston we fished for them with meat baited hooks suspended in a piano wire noose! Solves the bony mouth issue handily.