I took the sofa out today. It came out quickly. I messed around with the bump-out thing for quite a while before I figured out how to remove it. Here's the sequence:
BEFORE

REMOVE WINDOW VALANCE

REMOVE ALL EDGE TRIM

REMOVE FRONT PANEL

REMOVE TOP LEDGE

REMOVE THE UNIT

NASTY CAULK ON WALL. I tore the wall paper a little in trying to remove it. I shaved it down and will cover it or paint it or something.

READY FOR THE BED

The bed is going to have to be more complicated than I thought. For one thing the cargo door frame protrudes into the room about 1/4". I made a scale drawing of the two walls and I think I've come up with a plan. As simple as possible, but no simpler, as the saying goes.