Bastien Boots

I've never worn these boots so can't speak from personal experience, but the company description looks perfect for missionary use:

Bastien winter boots are headquartered in Quebec, Canada and have been proudly manufacturing winter boots to meticulous standards since 1932. The Bastien brand represents stylish, warm, waterproof boots. They are fortunate to have a team of five award winning footwear designers. The Bastien promise is to produce quality, casually styled, comfortable, fashionable winter boots. Winter is real. Demand the brand!

Here are some good options:



Also, here are some Blondo boots that look promising. Also waterproofed and insulated.