So, create a base that fits along your longest wall.
Then you make a set of interlocking slats, so that the lower set pulls out. These get screwed to the wall, on hinges.
Then add a leg to the slats that pull out and have your wonderful wife take two mattresses and cover them in curtain material to make two beautiful mattresses.
They can be arranged as a seat 
and when pulled out a bed!
Tada! Bed made now. We are booked to go away!!
