When we constructed the bunkie, I’ll explain that later, we just had the shell built and I did what I could to finish the inside.
After insulating I needed to drywall or paneling for the walls.
Being cheap I recycled some old 3 ft x 4ft masonite (composite board) panels. This was functional if not attractive.
We had a large pile of old National Geographic and calendars. Rather than purchase wallpaper Anne used the maps and photos from this source.
I think it turned out well.
The term Bunkie comes from cottage country. To make extra bedrooms many small garages were converted to bunk houses. To conserve air it was shortened to Bunkie.