Which rear light do you use? After something small that sits squarely on the super-skinny seat post.
Not a SuperSix owner, but an owner of multiple Aero profiled seatposts.
I use the Knog Plus as it is exceptionally narrow in 2 dimensions, and makes up for it in height.
You may need to change the length of the O-ring to suit your post size though.
Not the best as a Light, there is brighter, longer lasting batteries etc but if you need a specifically thin light, its good.
I use the same exact light on mine.
£13.35 delivered on ebay, cheers!