Alright. Went back with my laptop and CAN sniffing board. Aside from my board being a POS that refuses to capture two busses simultaneously, I confirmed that the charger <-> vehicle communications are occurring. The control is getting to the state where the contactors should be closing but doesn't seem to actually do so. Communication continues on the CAN loop until the charger aborts the session.
I tried to get a voltage reading from the contactor control loop but it decided it was no longer going to get that far. I have so many wires set up with extensions it's really easy for stuff to get a little loose in addition to everything getting really hot in the sun.
EDIT: Who would have guessed that in SavvyCAN, you check enable to enable CAN0 but for CAN1 you un-check enable if you want it to work too...
At least I don't have a fried CANDue shield.