I have a cigarette lighter style twin usb for the front power out – but I cannot see why you couldn’t do similar for the rear power point for back seat passengers.
Of course mate if there is a 12v outlet (fag lighter skt) ib the rear.
Agreed a roofbox would need proper looking into. It would be used to put any backseat drivers in lol.
On a seious note I need to take another look at the car including the torque of the motor.