I ran a primer plus on my dragster for years, best investment I ever made, cleaner oil, better control of engine temp, less alcohol consumption. Mine was a simple install, toggle switch on dash, get in car turn it on for a second or two depending on outside air temp and engine temp, I had pre-set the idle control for about 1200 rpm, used it for driving to and from staging, return road. My procedure was to drive it all the way to the water box on gas, make a pass on alcohol, flip the switch to gas on the return road, turn off the alcohol, drive back to trailer, turn off gas first, kill ignition. My wiring was way simpler than what you're describing, with any electric fuel pump I have always made sure I cut it off first in sequence. Congrats on the system, you'll love it.😁