The starting/chassis battery problem turned out to be a defective relay that's mounted to the undercarraige next to the battery tray. Apparently, it went bad and continued to drain the batteries whether the coach and chassis battery switches were on or off. I walked through with the mechanic what he did and where everything was located and how it all worked. Total damage was 200 bucks and a AAA tow.
Thanks again for everyones suggestions. If I experience any more problems like this, I have a better grasp of where to start and what to look for.
Nick Danger, Third Eye