Ammeter to Voltmeter...who does it?

Mattax said
Matt, You can still avoid out the extra splices and fusible link by leaving the alternator feed alone. For most people skills, that may be best. Agreed, a parallel wire through grommet would provide even higher capacity. Also agreed the motorhome with second battery that needs recharging is different case than the typical car.

One device thats available today which may help is the solar powered battery chargers. Connecting one to the coach battery would help keep it charged.

Ammeter internal shunt
1973 Imperial and Chrysler Electrical Circuit Troubleshooting Reference Service Repair Book from the Master Technician's Service Conference Session 311

So this sounds like the following drawing would be the way I need to go, since I would need a fusible link to protect the feed to the coach/house battery charging solenoid.

Click For Full-Size Image.