From the Class B forum topic: In Europe, motorhomes on this chassis are very common (read 70% are on the Fiat Ducato chassis). However, here in the US, the vans and chassis are just starting...
If I were to guess how it would work, I'd say similar to this.
Drop-down beds are not new, but generally tend to only be in toy hauler garages. However, in a US motorhome, I've never seen this in any shape or form. Murphy beds, yes. Not drop-down beds.