I have no idea if there is a precedent for this arrangement. However, if not one from the past there is now a precedent set.
My goal in building "Elsa" was to recreate the E&P coach "Palisade" as accurately as possible as to the body configuration and styling of the B&S exterior and interior. That much I have accomplished. However, the "Palisade" was originally a full coach which was converted in later years to a combine. I built the "Elsa" as an as built combine with the idea that we would have storage space in the express end and comfortable accommodations in the passenger side that were not crowded with a bunch of throw over seats. I guess that is my personal touch to the project. Like I said earlier it can always be changed at a later time if it does not work out as I hope.
As we all know cars were often converted to one purpose or another depending on the need at the time. Box cars were made into camp cars, passenger coaches were converted to combines, and others were once business cars converted to regular passenger cars etc.
Dan