Thanks, @davewill, for the advice.Those quoted temperatures should be for the ambient temperature to operate the unit in, not the temperature that individual components might reach during operation. It should work. However, if it's going to be installed outside, particularly somewhere that gets a lot of rain, I'd seriously consider going with the wall connector, as the mobile connectors aren't built for weather exposure. If you want to do the mobile connector, consider installing some sort of rain and sun protection for it.
The gen2 mobile connector manual does indeed warn that we "Do not use the Mobile Connector when either you, the vehicle or the Mobile Connector is exposed to severe rain, snow, electrical storm or other inclement weather." and "If rain falls during charging, do not allow rain water to run along the length of charge cable, causing the electrical outlet or charging port to become wet."
I'd need to have a covered box for the NEMA 14-50 outlet anyway, and perhaps I'll also hang weather-resistant tarp/vinyl over the whole thing to protect the UMC, and then just run it at lower amps, 20-24A or so.