I didn't want to mar the looks of my V7 III NP either - that's why I just use a Kriega US-30 without any kind of rack.
The loops are mounted on the frame and can be hidden under the seat if not in use.
You can even mount the Kriega longitudinally if you are careful while fastening (otherwise you will limit your seating position somewhat).
I always do this, even while carrying a ~50cm (20'') long pedal board in the US-30. No problems whatsoever.
I was very sceptical of the Kriega system. Somehow it seemed to be too easy to be true. But it's really super simple and works great.
And I can't see any obstacles why I shouldn't attach two US-20s to make it a US-70 either.