Hosefly,
I've worked on a number of "professionally" converted coaches, including Marathon, Custom Coaches, and Newells, Not a single one of them ever had an owners manual, let alone a service manual.
One of the problems is that many of the high end coaches is built to the new owners spec and there is not really any way of anticipating what that owner is going to want.
Even with something as simple as awnings, there are many different manufacturers and as many ways to deal with one.
My bus is an ex-trailways, ex-custom coach from their early days, like clear back in the late sixties, and the closest it had to a service manual was a notebook that had a bunch of old warrantee cards in it.
Good Luck on your quest for Magic Carpet Coach.... It seems that converters come and converters go..... often.
One thing that does come to mind though, didn't Sam Walker call some of his coaches, "Magic"?
Dallas