The devil is in the detail..
the reality is this.. You can do what you want to your helicopter and YOU are responsible for that.Stick a tomtom or a gopro wherever you want but if your actions cause an incident (Not Accident because you have deviated) you will be held responsible.
When I come across illegal mods to aircraft I remove and reinstate the machine to the documented standard .
As soon as you secure it to the machine or hard wire it you need a STC.
And all you pilot maintainers remember you are only allowed to follow the approved maintenance program so you cant install a camera unless the paperwork says it can be there.
But what do I know?