I bit the bullet and ordered an adapter from Tucson EV, it was less than me trying to source the plug and other bits to build my own.
My adapter looked slightly different from the stock picture above, the wires were not in a cable, just 3 wires.
I wrapped the wires in self vulcanizing rubber tape, and installed a water resistant plug that I labeled 220v.
I have yet to give this a test, but am anxious to do it. I found a nearby charger that I can connect to to check things out.