I made some progress on my BMS this weekend. I worked on the electronics up in the front of the car. This mainly just is the SOC meter and on/off switch. The pain is trying to fit everything I want into a blanked out dash insert. I think I have it all laid out so it'll work, but it took some time to put together.
Here is the blanked out dash insert with a hole cut in it for the SOC gauge.
Here is half of the circuit board that will mount up to the dash insert. The other half will have the shift register and voltage regulator on it. The toggle switch is for the plugin kit. The momentary switch is to put the Prius into EV mode.