Have you confirmed that the control for the parking brake motor isn't more sophisticated than a switch and power/ground?
Reason I ask is I am planning to build axle ends that use a 2015+ Mustang wheel bearing/hub and had hoped to use a later model Challenger parking brake setup along with the rotors and 4 piston calipers. Unfortunately, the Mustang hub is just too big to fit inside the parking brake shoes so that option hit the dust bin. So I started looking for a caliper that is only electric that I could use like the Viper or GT500 setup where a secondary caliper is used for the parking brake. I tripped over one explanation of EPB (Electronic Parking Brake - might be a Toyota term) and they talked like the ABS module and maybe even the PCM was involved in the process. I dropped the idea at that point but am wondering if maybe it is still viable.
So, I am curious if you are assuming somethings or if you have confidence in that.