Sorry to hear. Ok, back to basics, unfortunately. The wire in question, 37, starts at the starter solenoid, and without a break, goes to the c-211 or the fuse block. From there, it branches out to the headlight switch, etc; all areas you have said have no power with this gremlin strikes. So, the only logical place the intermittent issue can occur in are, 1 that one piece wire, or 2 that fuse block. I agree with Midlife that a break in that continuous wire is unlikely, but not impossible.
I think you have to pull that c-211 connector apart and check the connectors for #37 on each side to see if the wire to or post the connector look bad. It might be the pins themself. If the wires look ok, I would clean it thoroughly and see what that does. It’s got to be one or the other.
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