Range extender motors should have been easy to rent and much cheaper for long trips than a full car rental.

It would be very interesting to me to have a small sedan BEV with a rear charging port and an optional flat trailer with a large battery and room for luggage/furniture. The battery would be plugged into that car while driving. I'd want the trailer rentable from the dealer for occasional long trips. BEVs seem to have powerful motors, there must be something else with the economics why this isn't a thing.