Most of the 28 foot Argosy's MH's were a side pull out in the middle (between the kitchen and the bath). This was slightly smaller than a double bed width. This would be comparable to the bed room of a 27 foot Airstream Overlander trailer. Some had center twins. I have even seen a center twin with factory bunks!
All of the 26 footers I have seen were either rear twins or f they were rear bath, then they had 2 couches and an almost rear kitchen.
Our current 28 footer is actually a rear C shaped lounge that makes into a rear queen sized bed. We have a mattress there so we never make back into a lounge. I have seen the 78 as a rear twins too.
Rule of thumbs:
20 footer is a side pull out, but I have seen it with a rear Lounge.
24 footer normally is a rear twin.
26 footer can be rear twin or what some of us call a party coach, 2 pull out couches and a dinette.
28 footer can be center side pullout, center twins, or rear twins.
The way to know form exterior pictures if the bed is in the rear is if the rear has the wrap around glass, the beds are back there.
WBCCI #5501 AIR # 49
1978 Argosy 28 foot Motorhome
Wise men talk because they have something to say; fools, because they have to say something. -- Plato