Regency Tileset - Internal Gable

I built a small house with the regency tileset which has a base width of 3 foundation tiles. I used a Regency Angled Roof on both sides, with a Regency Peaked Roof in the middle.

I put some bedrooms on the very top floor (attic), but there is a gap beneath the peaked roof because there's no internal full gable to fill it. There is the Regency Gable End, which has roof components, but no indoor version.