Ok, loyal consultants, we are back from measuring, and my wife had some brainstorms. This is pretty much THE PLAN:
We are keeping the current sofa, (in the same spot) but I'm removing the seatback. (I used to teach metalwork so it's no biggie) The base cushion is ample for DW to sleep on. Behind it, as we all know, is a 6" dummy wall, that was probably put there for clearance. Its going. The remaining base of the couch will be moved against the wall. We will take the original seatbacks and reduce them to about 2" thickness, and find a way to mount them on the wall as something to lean against. When we are in 'living' mode, DW always takes a couple of pillows and lounges with her back to the fridge, facing the tv anyway.
The entire dinette is going. Once the freshwater tank is in place,(it measures about 30 x 19) all the old 23" wide dinette cushions (38" long each) will be made shorter to fit longways on the bench I will build (approx 70"). The seatbacks, that will now be the same length as the cushions, will be used for a 'flip up' for the bed on that side. They are 13" wide. They will flip or fold up on a hinge from underneath, and make the bed on that side 36" wide. This will still give us a 29" aisle when we are sleeping and a 42" area when folded. We will make some kind of thin cushion as the seatback for the former dinette-side bench against that wall.
I'm also trashing the ugly carpet for something with a better color and resilience.
I think this is a workable plan that makes good use of much of what we have. For dining purposes, I will be experimenting with an airline style flip up/out tray/table.
:W