It seems like the top of the vertical stabilizer would be good in your case. I fly with
two Garmin Virbs in my Lancair - one beside my head in the cockpit looking at the panel and out the windscreen. That one is plugged into my intercom system and records audio. I have a Virb Elite under the tail that has Wi-Fi and can broadcast to my iPad so in a pinch, I can check if my gear is down. I guess you won't need to do that
If you (or anybody) intends to record their flights, be advised that the Garmin Virb has a battery life of only 2-1/2 hours. Wherever you mount your camera, you may want to run some power there so you can get a longer recording time. In my case, I had to mount an external battery pack on the ventral fin.