If the cables are out of harms way, this may be
a very good way to go.
As long as you won't be stepping on them, or getting
fish hooks in them, I don't see why it would not work well.
I'm not sure if you need the flex conduit, but it would not
hurt.
Mike is right about possible interference.
Cables in close proximity to each other, running in parallel can pick up
interference from each another.