Some new updates:
I've stalled twice since the initial post. This morning I had an extended stall at a light (immediately after I stopped, with the stall longer than putting it in park, waiting a few seconds, then turning the key). Electronics were completely dead (including hazard lights) during this period, not just failed cranks.

The other night I was also unable to unlock the car via the remote, and had to use the physical key to open it. I've resoldered the joints on the RCM, so I don't think its that. I'll check out the voltage regulator, but I'm thinking it may be something else.