Vapor barrier is up on all walls and the ceiling, except for under the landing. I'm waiting on that until I get the light fixture.
Next was insulation for the walls. I underestimated the amount needed, will have to go back and get more for the ceiling, plus the light fixture and the drywall. There is a logistics issue with the drywall, as I need to borrow a truck to get it home. Not sure when that will happen yet.
Added some 2x3 cross-members to support the drywall between the stairs. This was easier and cheaper than running a stringer straight up the middle. Less wood, and will work just as well. This will also hold the ceiling insulation in place while drywalling.
Functionally, it is almost there. It already feels cooler, and it will hold humidity well because of the vapor barrier. I sure was sweating putting in the insulation, even tho it was about 66F.