It fits!
I epoxied two brackets at the back of the casquette, and will keep the battery and m-unit in place using a couple of zip ties around the forks. (I added some eva foam to cushion them from vibrations and pressure from the zip ties. Both are also mounted to a steel plate.)
This is my electrical schema now:
As for the stuff on top, I've pulled the old battery, solenoid, starter relay and start button from the bike, and keeping it separate. Whenever I need the electric start (when working on the bike), I can just hook that up to the start motor.
I'm converting the lighting to all-DC to simplify things. (Otherwise, apart from the extra AC regulator/circuit I would also need two more relays to control them from the m-unit.)
I'm dropping the two brake switches (the front one since I'm going with 50's style controls, and the rear since I'm getting rid of the toolboxes.) I'm replacing them with a gearbrake, which lights up the brake light whenever the bike slows down, or when it's in neutral. The audicator is controlled the same way.