Doug, I feel you have excellent technical experience and I enjoy reading your recommendations and solutions to problems. It was 'emphasized' to us at delivery to only take the coach to a Prevost service center for engine/drivetrain/service and back to the converter for house repairs.
A tech that is not familiar with our type of electrical systems (24 volt AND 12 volt) could cause more problems than they fix. And, our coach has three Lithium Ion batteries for house and regular batteries for starting and genny.
Safe travels to all,
MM.