Installing the tower wall is challenging. To prepare, sand the slot on the porch roof to prevent any wooden splinters from snagging as the wall slides in. This will also enlarge the slot. Despite these precautions, you may still need to repair any wallpaper damage after the wall is in place.
Once the wall is secured, I can add the ceiling and floor trim. It's important to be familiar with the positions of these trims to avoid interference with the side tower wall. I also installed the interior front door trim, but I can't address the second-floor door yet, as I don't have it.
While browsing the paint section of a craft store, I found some clearance paint in a lovely mauve color. I decided to use it for the dollhouse, replacing the gray porch floor. It looks much nicer and fits better with the overall color scheme.