Honestly, I'd probably just purchase a cheap Chinese EVSE. It would be cheaper than evseupgrade would have been and offer you more current. I suppose the absolute cheapest method would be to upgrade your OEM charger yourself and make it just a 12a L2 but when you'd consider your time and the fact you can purchase a new 16a L2 EVSE for <$200 I'd think that might be the way to go.
Also not sure if it's still available but there was someone here on MNL selling their used Chinese L2 EVSE for a great price, of $130 shipped and that one goes to 20a and is adjustable, that's what I'd get if I didn't already have several L2 EVSEs of various charge rates
At the time evseupgrade was a viable deal, I did mine at the time but only because mine could be upgraded to a full 20a, a few years later and they maxed out at 16a because Nissan cheaped-out and used thinner wires.