I was mistaken. RV adapters don't work with EVSEs because an adapter intended for RVs connects grounds, neutrals, and one hot. An adapter intended for EVs connects grounds and both hots and leaves the neutral unconnected on the station side. So this is what I need: NEMA 5-15P/5-20P to 14-50R 120V Adapter for EV, 3 ft. – EVSE AdaptersSo the adapter you linked to is almost perfect, thanks! The cord is not really necessary.