Thanks to everyone for the good advice.

I went ahead and bought some heavy hunting/hiking socks and sock liners. The socks are 88% Merino wool, 16" tall. The sock liners actually do a pretty decent job of keeping my feet less wet than normal (I won't say dry, because they're still slightly moist, but it's a vast improvement). And since the socks are so tall, I'm doing a turn-over to the inside to bring them just over the tops of my leggings. Works great!