I remember reading in "The German Giants", many years ago that some of the German R-planes had pretty enormous crews, with the Captain I believe often not the pilot.
Does anyone else remember the book? It was written sufficiently long ago that the author interviewed surviving crew-members and I always remember that one of them, asked what it was like to fly a Staaken R6 (or whatever it was called) remembered "we sweated like pigs".
Some of these aircraft had inboard mounted engines with propellers on outriggers driven by shafts or gears (highly inefficient and unreliable) and so had large crews on board to include engineers.
However, most sadly, I don't have a copy of the book to check.
Even so, it is surely true that the rigid airships of the 1920's and 1920's must hold the record for the largest flight-crews on a 'flight-deck'. One of the British rigid's (R34?) crew compartment survives, I think, at the RAF Museum at Hendon.