Q) Is this a new condition that just started or have you had something changed or added to your system?
A) New condition. Everything has been working well all summer with no changes since.

Q) Does it trip if you have the breakers for the charger and hot water off when you plug in?
A) With breakers off there is no load and it does not trip. (Maybe that tells me the fault is on the "house" side and not the shorepower connection? I'll check to see if a load on the water heater circuit trips -- so far I've only tried the charger circuit.