First off, all along I've been calling it the wrong thing. It's a tank top, or a sleeveless shell, or something. Not a sweater. Sweaters have sleeves.
Next off, I said it was all done, and then didn't put up any pictures. Now I'll put up pictures and give an explanation.
I really like this yarn, DK Shine by Knit-Picks, if feels cool and wonderful against my skin and has terrific drape. In fact, this must be the most 'relaxed' yarn I've ever worked with. Even though I got gauge with my swatch, this tank finished with far more positive ease than expected, especially in the back. I think I could've gone down a needle size, and even then, I should have knit the back a size smaller than the front.
Here are the pieces together.
Overall, I'm reasonably pleased with the results.