Unexpected data:
First, the shoes seem to be working better. Not sure if it's the compression socks or one more round of heat molding, but ~6 hours on the bike today resulted in intermittent numb toes and a very little brief foot pain.
I measured my feet before and after today's ride, to see how they swell.
Right foot:
Circumference around ball: 281mm before, 279mm after
Instep: 288mm before, 284mm after
Left foot:
Ball: 288mm before, 280mm after
Instep: 290mm before, 280mm after
Not terribly drastic changes, probably within the margin of error, but it appears my feet actually shrunk slightly. Entirely the opposite of what I was sure was the case.