Yes, I know that was lame, but I told you that was what the problem was. (Not the lame, that's a condition and I can't help it. I mean the electrical from last night.)
I was tracing back the circuitry and came across this guy.
It's one of the few connections I didn't redo while rewiring the bike. It looked properly done, solid, and it tested out fine originally so I decided to reuse it. This is the ground wire (despite being red) that connects the rotary dash switch (on the tank) to the frame. It had pulled out and was sitting loosely in the shrink tubing.
I redid the connection and, sure enough, the accessory circuit and the lighting now work mostly as expect. I say mostly because I also noticed a slight issue with the rear turn signals but more on that in another post.
I also noticed the starter wasn't working. The relay seems fine but the solenoid doesn't seem to be functioning. I can jumper across it and the starter kicks in so, rather than debugging much more, I think I'll order a new solenoid. To be continued....