They kinda go together, don't they.
I've been working on different camera positions lately. I have two GoPros, a 3+ Black and 3+Silver. The silver one is usually inside mounted, comme ça:

That's a RAMMount it's stuck to. RAMMounts Never Ever Fall Off, unlike some other suction mounts. The GoPro is in the skeleton case and can be semi-perma-powered using the ring cupholder (which also provides power to the BlackVues).
My understanding is that the gopro adapter should be used rather than just jacking the cam into a generic USB powerline, as the voltage needs to be stepped down, similar to most modern GPS devices. I met someone at the Ace Cafe whose GoPro failed after using generic power.
Sometimes I use a GoPro suction mount on the passenger side window looking into the cabin, especially when getting track tuition.
I also use this:

It's a Rennline folding towhook with a GoPro mount. Some circuits like them ... most UK circuits I've been to so far seem to be ok with them, Nordschleife not so much. The low mount position gets excellent results, especially at higher resolutions. Disadvantages are that the sound is bizarre (mostly slipstream) and obviously provision of external power is a problem. I don't use it on the road that often, but reactions from people seeing the towhook cam can be interesting ... I've got shots of a very pretty tourist gal in Bruges taking pics of me and smiling and waving.
The GoPro remote controls both cameras (and can control up to 50 of them), so it's one button press to stop and start both cams. The remote has no problem contacting the externally mounted cam.
I've been trying to get Harry's Lap Timer to control them, so far without much success, but that's a whole nuther story.
Anyone else using these cameras for track or road use ? Would be good to swap tips & tricks if so.