Back in the mid 80s winnebago made some class a rigs with a pull down double bed over the driver and passenger front seats.
Rv drop down bed mechanism.
The happijac power bed lift is easy to operate and perfect to maximize space in toy hauler garages by lifting beds out of the way to make room for motorcycles or atvs.
It was on some sort of spring loaded mechanism and came down almost to the top of the front seats.
This design by brian rogers uses lift supports to raise and lower the bed from the ceiling.
If you scour youtube there are a number of people who have designed custom drop down bed systems.
These are a hybrid design between a platform bed and a convertible one.
The nearly silent bed lift system is operated by a single motor that controls four support mounts to raise and lower the bed at 2 3 inches per second.
The straps retract into the bed base concealing the lifting system while in the retracted position allowing oems more freedom in floorplan designs.
Powerful heavy duty bed lift solutions.