You're correct, that is the IVR routing, but mine steps it down to 5V, per my service manual. Here's a different angle of the circuit board, before I cleaned up the copper with BarKeeper's Friend.
on edit: I just took a look at my service manual again....that circuit breaker on the back of the ammeter is for the trailer towing package. I guess I do need to save it and just tie it inline with the battery positive post and the alternator output wire going to the battery, as you said. I don't know how people get along without the original Mopar Service Manuals.