I ran wires for the autopilot autopilot and got it powered on and talking. Lucky for me it fits perfectly in the panel, so I guess my CAD drawing of the cutout was accurate.
Here's a closer view. Notice that my panel has an on/off switch for the autopilot, so if it tries to kill me I can return the favor.
The autopilot is too deep to use a standard D-sub connector (it hits the subpanel) but I was able to make it work by using an expensive right-angle D-sub backshell. It was pretty dicey to get the two halves of the backshell clamped together and the thumbscrews inserted without pinching any wires.
All the fuselage wiring for the autopilot is in, but I haven't installed the connector for the pitch servo or the wing root disconnect for the roll servo yet. I'll do that later.