Desperately dull, I know, but what has your insurance company said about the vehicle mod?
(i.e. "No problem" - "Amended your premium")
Depends on your policy actually. Certain policies want to know additional equipment permanently installed into the car, that you will have to declare, these will be covered. Although this method says its hardwired, nothing is permanent and can be removed instantly as in reality its just hiding the wires.
If you look at the link I posted you will see there was no modification of car's wiring in anyway and all wires are removable. + I always remove my dashcam and sat nav while exiting the car so my install (in my opinion) is temporary and is not covered for loss anyway. Now if you install an aftermarket stereo that is full view that is a mod for sure, this is just hidden wiring for temporary devices.
Not to say its not worth speaking to your insurance about it.