IMO the power bank option will work. Just plug the cam into the powerbank with a cig lighter to USB adapter when you need to be in parking mode. Have 2 power banks and charge them in your home and rotate. You charge your smartphone each day so whats the big deal. The real issue is the wear and tear on the cig lighter end of the dash cam cable. Doing this daily is not practical and you would probably have to rewire when it wears out.