probably ok on the o8 to kill the fuel but 03-07 the injectors don't like to be dry so the starter relay signal is the best IMHO
even then I don't know what wire Sandyc because without some research you may throw a code ?

 

yep, after 2008, almost everything you've listed here is contained in the Programmable Control Module (PCM). The GEM is extinct, and the SJB houses most of the modules. The ACU has its own logical inputs (redundant audio controls).

The easiest way to demonstrate this is to pay attention on a 2008+, when you turn the headlight switch from off to headlamps, there is a noticeable short delay in the lights coming on. The delay is caused by the clock speed of the processor in the PCM.

 

Here is a thread with info about converting the upfitter switches to "always hot" rather than only hot with the ignition on, it's just a matter of removing a relay and adding a jumper wire between two of the sockets where the relay was:

https://www.ford-trucks.com/forums/6...-switches.html