The other day I went out and bought the $10 blow dryer from Canadian Tire. I dissected it to get the heating coils out of it. Built into the coils is a bimetallic temp control switch and a thermal fuse for safety.
With a healthy dose of duct tape and a few screws I installed this unit into the pipe that connects the blower fan to the the heater box:
Instead of 120VAC, the heating coils will be powered by 72VDC in the car. That doesn't sound like a lot (40% less voltage) but I did notice that no matter what speed I ran the heater fan during the test, the air seemed to stay the same temperature, indicating that the bimetallic temperature control was hard at work doing its job. What this tells me is that 120VAC is way more than enough to maintain the target air temperature at any fan speed, so 72VDC will most likely be enough [at least] in the lower fan settings.
In other news, I spent lots of time making battery cables yesterday. I had plenty of 4/0 truck battery cable to do the job. Armed with a borrowed terminal crimper and 36 copper 3/8" battery terminals, I got it done. Today I made a bracket to mount the contactor (the main disconnect relay that all traction power goes through) and I mounted the controller. Once the control board (literally board. It's a piece of Ikea shelf) is more complete I will post pictures, mostly just to confuse everyone, including myself.