Use 80# leader, tie to the mainline with an alberto knot. If you are concerned with visibility buy flourocarbon leader material.
You're idea isn't bad just a bit overkill. Imagine trying to rig that up in the middle of a blitz at night with no moon. Remember the simplest solution is usually the correct one.
I just mainline bucktails and swim baits on the 20” …
I would use a shock leader here as well.