Splicing into the wires at the BCM to install resistors for the turn signals worked fine. I have them temporarily connected for testing and will wrap everything once I get the towing harness spliced in.
I also crossed off a bunch of smaller items, like wiring in the 3rd brake light, AFR/boost gauges, and turn signals by the headlights. I also filled and tested the IC circuit. I was putting it off because I expected multiple leaks with all the connections that could fail. I only had one leak at the front where the pex line meets the elbow going into the HE. It was a simple tightening of the clamp and the leak stopped. I didn't want to overtighten the clamps and deform the end of the pex line, but it didn't take much tightening to stop the slow leak.
I'm picking up my rear tunnel cover section from powder coat today, so I am hoping to have the tunnel buttoned up this weekend and the parking brake tested once I can bolt the handle in. Once that's done, I need to get the initial alignment done so I can take her for her first test drive.