FWIW, my coach is connected to 50 amp service at the house. I was wrong. The light is not part of the switch but a separate light next to the switch. Unfortunately I do not have the electrical diagram that shows that switch so I can't determine how the indicator is wired. I will request that diagram tomorrow morning.
Here is my Main Power (USE/Store) switch in the "Off" mode.
Here is the Main Power switch in the "On" mode