Ammeter to Voltmeter...who does it?

Yes. If you run a charging wire to either the solenoid, the relay or battery post, all power for charging will be diverted from the bulkhead connection and dashboard ammeter. You may still see some flow on the ammeter during start, because that might be be the shortest path from battery to ignition switch. 5 amps at most, less if some goes the other way.

It could be the insulation - in the photo the alternator output wire bulkhead to looked heavier than the battery feed.

My question about the regulated power supply for coach was for calculated current loads. I don't know about a fridge. For lights, if a bulb is rated at 12.8 Volts and is given power at 14.2 Volts, more current will flow through it. So if adding upo current loads, something to keep in mind.

This circles back to your question about the alternator and whether the original blue tag one will do the job. And yes, once the direct charging wire is added, the my question is whether the 60 amp has an advantage because it is self limiting. In other words the recharging rate will be 50 amps or less even driving on the highway. Lets assume 55 amps at 14.2 V, less whatever starter battery needs to get recharged, less equipment needs (5 amps for field and ignition minimum).

Now lets say a '100 amp' alternator can put out out 90 amps at 14.2 Volts while driving 35 mph or faster. That would let the coach batteries draw as mcuh 85 amps when they start to recharge (assuming they were very drained).
Might see what battery manufacturers recommend. These may be deep cycle batteries which might be OK with it. This isn't that different of a situation than boats with cabins, or airstream and other rvs.