Today I spent some time testing the remaining portions of the 12 volt system and all the components I've hooked up to it. Admittedly I haven't checked all the pre-existing 12 volt powered things on the car, I'm just assuming they'll work because I haven't touched them. They worked after the engine was removed, I think they should work now.
I got the replacement off-delay timer relay today, dropped it in and it worked perfectly. I've got the time set to 10 seconds. I figure that should be adequate to prevent any damage to the power steering pump due to short cycling.
I checked that the kill switch on the charging door works properly.
I tested the DC to DC converter relays to be sure they are working. When the car is running, those relays will have power to them and cause the converters to jump their output to 14.2 volts. That will help to keep the accessory battery up to full charge.
I installed the smaller DC to DC converter that is specifically for the Link 10 meter. It will isolate the 12 volt system from the high voltage pack, which are wired together at the meter.
I made sure the fan for the battery pack has power to it. I haven't installed the temperature switch yet, so that test will have to wait for later.
Last, I started testing all the relays and switches for the heating element. Ultimately I found that the dashboard switch, which should only have power to it when the heater blower is on, was live all the time. It took a couple minutes but I isolated the problem to a relay that I'd bought at Fry's Electronics. The coil seems to be frozen closed. I don't know if it was like that when I got it, or I did something horrendous to it and broke it. It's probably that second thing, but I honestly don't know what I could have done. Fortunately, a replacement is cheap.
Still no word on the batteries. Stupid slow container ships.