I take that back
Going the headless install with just a few buttons was going well until I found a nice LCD built for my car, for a very reasonable price. Combined with a few other devices, I decided to go ahead and remove the factory head unit completely.
I chose to go with:
Touch Screen
JoyCon (Steering Wheel Controls)
GMOS-01 Integration Harness
Everything else is installed and working with my old lcd that is still flailing around in the car. I still need to find a better place for the 2×16 serial LCD that currently sits on the dash above the DIC.