If you put a sofa in the rear, will you be taking out the side lounge and replacing it with a credenza or a dinette? Otherwise I think your best bet would be to have an L shape as in the CCds but extended through the side lounge. Otherwise you might contact Flex Steel as they do custom work for frames and interspring contruction. Just for some ideas Flexsteel Marine Furniture and Marine Seating.
I think if I were to change your configuration I would have a custom u shape sofa and continue that to the refrigerator wall with a removeable post circular up/down table or a free standing stow away fold-out or leaf-up type table or along the lines of the newer Safaris and perhaps a storage cabinet under the monitor against the refrigerator wall. But the neatest thing might be to copy the layout of the largest Airstreams and put a corner table away from the door and two upholstered loveseats on either side.