Almost impossible to sort out a safe ground. Sure there are experts that can advise, but it is V2L where you plug a device into a socket that is on the end of a lead connected to the car. It is not intended to be a cheap shortcut for V2H. How often do we see power failures in the UK? Since moving into out home nearly a decade ago we have seen none. If there was one then I have an extension lead that I can plug important things like the fridge and freezer into, as well as the less important broadband router, TV and SKY units. We use low wattage LED lamps, so these could also be powered.
Of course, people will try