Hanging down a GoPro from your harness is not that difficult and costs you only € 1,95 and half an hour of work.
In my example I was using a GoPro Hero 5 Session as I barely see any differences to the Black and the size of the Session is simply perfect for this use.
What you need:
Cut the Aluminium Angle into two approximately 40 cm long parts. Bend the Aluminium Angles as shown in the pictures and connect them with the rivets on each side.
Connect the Angles on the 10mm side, so that the GoPro´s camera angle will not be affected (in wide mode).
For keeping the GoPro in place, I cut of small 8mm Aluminium Angles and reveted them on both sides of the GoPro. You should also cover the aluminium with some Armaflex or tape to avoid scratches on the aluminium housing of your GoPro Session.
Connect the rubber band as shown in the picture. For a 77 gramm GoPro it does not have to be verry strong.
Mount a safety leash to secure your camera in case it does fall out.
When putting your GoPro into the "Hang-mount" you might have to stretch the two aluminium angles appart. Usually this is no problem and the tention fixates your camera already. Of cause you should use the rubber band to additionally keep it in place and connect it with the safety leash.
Pictures work pretty well with this mount. For the stability in videos I need to do further testing and maybe attach a badminton ball to sabilise it a little.
Most important, learn propper wingovers, assymetric spirals or infinity tumblings as pictures without landscape are pretty boring ;-)
All the best
Tom - your Paradealer