Yeah I was going to suggest bicarb & vinegar... and lots of sunshine!

The tea treatment of the feet is a great idea! hadn't heard of that before.

Is there something you can line the boots with or some way to de-stink the boots? I know some shoes cause stinky feet more than others. My mum has a pair of sandals that make her feet STINK lol. But normally she doesn't have stinky feet.