Yes. I've seen more than once when someone has found himself an adapter cord and used it inappropriately.As you know, the problem with these kluges is that they frequently get out of the "lab' environment and to folks with less knowledge. Even good labeling frequently doesn't prevent dangerous usage. One reason I like the extension option (#12 would be my preference) is that it makes explicit the expectation both need to be plugged in.
The biggest thing I can tell everyone is that if your insurance company finds you were using a) non-code-compliant installs and/or b) non-UL listed appliances / cords / etc., they may not cover your loss -- even if it had nothing to do with your charging. This is because they can make the presumption that if you didn't use compliant installations for your car, you didn't use it elsewhere as well.
It's a code issue. Any use greater than 3 consecutive hours is rated as a continuous load, and when continuous loads are used the circuit must be sized at 125% (with a few exceptions, where *every* device -- wire, junction box, breaker, etc. -- is rated for 100% duty cycle). Allowing it to be overridden is just asking for a lawsuit. Should you want to do this, your best bet would be to take the J1772 path and build a larger pilot signal.BTW, I kind of guessed the UMC used the adapter to select current (how else could it know wire gauge!). It's a shame it selects 80% maximum. In my case I connected a 14-50 with #6 within 18" of the main panel to a 50A 2-pole breaker. The breaker is connected to a separate meter (SCE provides a better TOU rate with a second meter) I really should be able to get 50A no problem (assuming the UMC was properly rated).