simple and Taz,
We did something similar in our 64 Safari (22') several years ago. It was the dinette model floor plan so it had the large window on the curb side in front of the door. That allows more room for a bed to go in lengthwise in the trailer. We wanted to be able to each be able to get out of bed on our own side like the newer 27' Front Bedroom models. We shortened the street side gaucho and moved the refrigerator aft about 6 - 8". That gave us enough room for the bed. To your point Taz, we originally started with a bed that folded into a couch and coffee table. When the bed was extended, the coffee table became the foot of the bed. We used new gaucho slides from VTS for the slats and put two pieces of ¼ inch plywood for the mattress base. We used high end crib mattresses and the sofa back as the cushions for the sofa and mattress for the bed. We found that we would deploy the bed on the first night of our travels, then leave it that way until we got home. So this year we put a full size Euro-top mattress and leave the bed set up all the time. I've included a sketch and photo, hope it helps as you design your solutions.
As a side note we're about to do something similar as we work on our 68 Overlander (26'). I think I've figured out how to do a sofa with three sections that pull out and I spotted a mattress at Ikea that I can modify to fold into sofa configuration. The 68 is more challenging because the door is set further forward with less distance between the front wall and the first "difficult to move" interior cabinet.
Good luck and please PM if you want me to take some other photos or want to toss some ideas around.
Roy and Marie