Just to follow up...
I bought a pair of Simms Freestone wading boots at Kiene's a while back and finally got a chance to try them this past weekend. So far so good. They worked well with my fins and my feet felt OK after about 11 hours total in the water over two days.
The true test will be the week I spend in B.C. next month.
Thanks again for all the replies.
Bookmarks