Yikes, $15-40 for those watertight connectors? I'm not going to grid charge outdoors, so I was thinking more like this:
The charger is installed in its final location. Its AC power cord exits the IMA box through one of the many vent holes back there. With the IMA box closed back up, you wouldn't even know the charger was there except for the power cord chilling out in the spare tire well.
I jumpered the always-hot MCM pin B10 (white/red) to MCM pin A11 (pink/blue), which powers up everything on the IMA fuse. N.B. this does not include the inverter fan or DC/DC converter. The BCM and current sensor are powered and the battery fan should be live, and it keeps the SoC gauge accurate. That way I don't get a forced regen (wasted fuel) and a recalibration first thing in the morning.
I also jumpered the DC/DC converter power wire to the above-mentioned always-hot, and that didn't go well. It powered up the DC/DC converter... and everything on fuses #1-7, including the ECU, O2 sensor heaters, etc. The more I study the circuit diagrams, the more I think you can't run the DC/DC converter without running the ECU and the "electrical load detector".
I may resort to a cheap, automatic trickle charger permanently installed in the car and powered by the grid charger's cord. Or I may give up on grid charging the 12V battery.