Re: Whisper it…
"Maybe future trailers will include supplemental batteries to compensate for reduced range?"
A EV drive train developer, AC Propulsion, built a limited number of Scion van EV's and had a small trailer with a 1000cc (ish) generator that also had space for some luggage. It turned a BEV into a PHEV and would be a great option that dealers could rent to EV owners when they wanted to make a long trip. All it would take is a hitch and an electrical connection that interfaced into the electronics already on the car. About the only change would be that the car would recognize that the trailer was hooked on since they won't let you drive the car if they sense that it's plugged in. An argument with Hybrids is you have to lug the weight of the engine around even when you don't need it. With a range extender trailer, you leave it off when you don't need it and can hook it on when you do.
Using petrol to generate leccy is a horrible expensive way to go, but it can make sense in some cases when you want to go out past the charging stations. It's still cheaper to use a public charger when you can and it makes sense to stop for meals/restroom breaks at places where there is one.