As most of you probably suspected, I ended up with outcome #5 - the full wrap sweater. I finished the sleeves last night, put the body on scrap yarn and tried it on and yes, there was a significant overlap in the fronts. My intention was to get outcome #2, but I somehow failed to realize that when you increase BOTH FRONT PIECES at the same rate as the back piece, then the front ends up with twice as many stitches as the back. Hello! I should have omitted the M1 increases at the outer edges. Oh, well. I'm lucky I didn't end up with outcome #6! Based on my preliminary fitting, I think I will still end up with a nice and well-fitting sweater that I will actually wear. It's not as fitted as I would have thought, though - I should have gone with the 17" size instead of the 18". I suppose I can make up for this by not going as far with the front increases and then wrapping the sweater more tightly.
It still looks like I'm on track for finishing this by the 31st. I was worried at first, since there has not been much knitting chez the Croissant for the last few days - we were all taken out by a very aggressive stomach bug. Trips to the emergency room for the Wibbles and everything. But we're all fine now, and we even managed not to get any of the grandparents sick.
(I am also happy for another, secret reason, which I hope to reveal soon.)