No need for a trailer, since a typical EV already has more capacity than most home battery solutions. Example: A 2021 Tesla Model 3 Long Range AWD stores 82 kWh[0], while a PowerWall 2 only stores 13.5 kWh[1]. So a single Model 3 is the equivalent of up to 6 PowerWalls. All it's missing is official support for vehicle-to-grid connections.