Not the subject of this AC but do you think that a GoPro mounted internally does not require design approval? It is the very same regulation that powers this AC.
Incidentally, the EFB CAAP states that EFB mounted to structure only requires design approval. (is my cabin door part of the structure?) Silly to mount anything like an iPad or GoPro on the flimsy interior trim in my airplane but sensible onto a convenient steel tube.