Go to Seattle Ship Supply and pick up a pair of Red Ball "Bama Sockets".
I have wore them for ten years, working on decks of fishing boats, under my xtra tuffs, and also under my stocking foot waders.
Nothing can match them. I think they cost about 12 bucks and you will notice the difference. If your waders develop a leak or you go over the tops, these things absorb any moisture, or sweat and wick it away from your feet.
Just buy your wading boots about a size larger than normal.
You will love them, I know I do.
Hope this helps.