And so we began the search for a different tub. Now we needed a 32X60 tub that was deeper than normal, and not cast iron. (No way I'm hauling 300+lb tub up the creaky stairs, nor does the floor need the extra weight.) Not many choices out there for a deep 32" wide tub. Lots of whirlpool options, and lots of normal height options. We narrowed it down to a Sterling and a Kohler, and picked the Kohler based on looks. The apron design and general lines of the basin should match the style we're going for in the bathroom better than anything else we've seen that would work.

Picked it up this weekend, hoping to put it in next weekend. This thing is a LOT more solid, and I'm definitely a lot more confident in the quality of this tub. (Koher Devonshire Bath ~$500.) Still only 80 lbs, so it will be easy enough to manuever into place. Unfortunately, the drain is 1" farther from the wall, so I will need to redo the drain setup. But I'd rather do that then redo the tile later.
Other than that, electrical work is happening now. I'm hoping the bathroom part of that will be done this week.
So next weekend, get the new tub in. Then insulate around it and put up the cement board walls. Mud and tape the cement board joints and then we'll seal the entire assembly w/ Redgard. Then we can tile the tub area and put vinyl trim up around the window. After that, drywall, primer, paint, flooring, install sink and finish shelving behind the toilet and next to the tub. And I'm hoping to have that done by Halloween. It will definitely be a challenge!