Thanks. Yeah, looking at the Autocad drawing, it doesn't appear to be a high ceiling room unless there's no way for that to be represented on the 2D plan. Looking at the side renders I attached, the siding is different (it's board & batten at the bottom and fiber siding at the top. I was thinking maybe there's some trick to doing this in the attic? I tried that but it just stuck up through the roof.
I guess I could try adding a room divider in that section, make it taller and then make those walls a pony wall with BB at the bottom and siding at the top? Is that the correct way to do it?