Using an Electric Vehicle as a Toad (on a trailer)

I always though an Hybrid electric vehicle, with it's huge LI battery pack, and having its wheels on the ground, using regenerative braking to charge the battery would be a great toad. Once at the camp site, plug the RV into the toad and have enought battery power to run the AC all night. While sight seeing the next day in the toad, the battery could be recharging for the next night. Brilliant!