All very interesting. My 1971 Caravel has similar problems. Can't make sense of how the cushions fit, and I doubt I'd be able to sleep on them if I did get them to fit. Making up the bed and then unmaking it to have a place to eat seems like a whole lot of fuss and bother.
I'm thinking of removing the whole sheebang and putting in a proper mattress with some sort of table I can pull up and swivel over and eat sitting on the edge of the bed. Or perhaps just find an old TV tray or two with a little place to stow them.