I have a 3rd-party go-pro mount inverted and bolted to the underneath of an out-front mount designed for a Garmin head unit attached to my Vision integrated cockpit. The specific mount you get depends on the model of cockpit you have. There should be an appropriate hole, hopefully two, that you can use to install the GoPro mount with a small bolt and nut.
The Varia is attached to the quarter-turn Garmin mount via a standard Gopro mount, so just remove that and bolt on to the GoPro mount attached to the underside of the Garmin mount.
