Next step on the Grand Unified Couch Theory is the cushions. Fortunately, my mother is a professional interior designer with her own workroom, so I can cheat. Thanks, Mom!
And just like that, we have cushions overnight. We made two identical cushions for the seat and one slimmer cushion for the back. But because of how shallow the seat is already, and the fact that the back is constructed of 8-way hand-tied springs anyway, I think it's more comfortable without the back cushion.
Slumber party mode uses the duplicate seat cushion to make a flat mattress. It's a twin mattress, plus about an inch of width.
I Scotch-Guarded all the fabric to make for easier cleaning. Since this is our only living room seating as well as Luna's favorite sleeping and squirrel-viewing area, Scotch-Guard was a no brainer. It took four cans to do two coats.
The shelf behind the couch is made out of a scrap of oak butcher block I had left over from the countertop. It's both a console table and support for the back of the couch in "lounge mode," and a nightstand in "slumber party mode."
I built the drawers the same way as all the other drawers in the Airstream using this method and these soft-close drawer slides. The drawer fronts are made of a single piece of oak 1x10 so that the grain matches across all three drawers. The hardware are salvaged letterpress drawer handles from A Vintage Parcel on Etsy.
I'm pretty happy that my Gransfors Bruks small splitting axe fits perfectly inside the drawer next to the wood stove.