The Road Runner by Sun Valley is the only contemporary make I've seen that does this. I saw one a few years ago. If I remember correctly there were piano hinges attached to a lighweight platform that swung down from the ceiling when it opened. The ceiling over the dinette was slanted, sort of like a Aliner. So, when the bed came down it was parallel to the floor and at an angle to the roof. There were wall catches, a piece of wood about the length of a 12" ruler and about 1" thick, on both ends of the dinette wall that the platform lay on for support.
I really liked the floorplan but did not like that the RR overhead bunk was rated for about 100 pounds or less. The walls just were not sturdy enough to support more weight
. A piece of cheap foam lay atop the platform.
You raised the bed by pushing the platform up so that it was flush with the ceiling. I'm fuzzy on this but I think there were straps on either end of the platform that secured the bed to the ceiling.