I did also find some of the other HMI program's (Human Machine Interface) ports that were of interest to me...
Subtle, but this is how my screen should look above the buttons.
Yes, there's a port to turn off the dual zone output, and a port to turn on the single zone output. The buttons are controlled by the smaller microcontroller (they call it the V850 in the startup scripts)... So, I still need to use the middle fan controls, and the left "passenger" temperature rocker button does nothing still... But at least things are in the right place (for me) on the screen now!
The "Gauges.ino.elf" program now accepts a parameter of "1" or "2" to override the number of zones displayed.
(Yes, I've got the extra servo needed for a dual zone conversion, along with Forscan to reprogram the HIM, but I chickened out of pulling out the whole dash to install it... One day though.)