Gene and Ricky, thanks for the feedback.
I'm not enough of an electrician to understand the schematics (can't even find the converter on them), but the logical design to me would be for the converter to feed the 12v
panel and for the batteries to "float" on the system. If that's the way it's done, turning the converter off would simply leave the batteries to feed the 12v
devices (and discharge until shore power or TV power is restored).
Gene, my take on the service manager's comment was to use a simple timer that would otherwise control a living room lamp or similar, reasonably low amp fixture, in the home. The 120v schematics show 8a allowed for the converter, so I assume any timer rated at 15-20a would work.
How the "kill switch" fits into all this is another question. I think the intent there is to disconnect the batteries from the system completely to prevent battery drain. If this is the case, using the kill switch would not have the same effect as a timer on the converter and would not allow me to use shore power without charging the batteries.