I ended up moving my rear mount. I bought the K-Edge saddle mount and used a couple of the adapters from the Garmin miscellaneous accessories pack to put this together. I didn't want to lose my under saddle bag, but I didn't like the vibrations and angle of having the VIRB attached to the frame. So this is my current compromise:
He is some video from when it was attached to my frame. It's during a slight decent where I decided to have some fun:
I'm hoping that moving my rear-facing VIRB to the saddle will reduce that vibration some. We'll see.