One issue I frequently dealt with was the charger shutting down due to over heating. I would finish work and come out to find a car with less than full charge. Luckily most of the time it had charged enough to still get my home, but I found myself a couple of times sticking around work another hour or more. The temporary solution was to leave the trunk slightly cracked during non winter months and this did the trick.
I plan to ensure adequate ventilation this time and have installed two 120mm fans. They will connect directly to the 240v charger source and run continuously during the charge cycle. The fans are quiet (30 dB), low speed (1900 RPM), move up to 67 CFM and take 7.5 watts of power each.
Here is a shot of the mounted fan. The trunk is big ugly at the moment but I plan to reinstall the carpeting after the modifications are complete.
Here is a shot from the bottom of the trunk. I've installed a vent which will deflect water spray while driving. They are angled to take the incoming air which should close the vents as well during speed.