I wear a padded cycling short designed to go under pants. I cut the tags out and I can't remember the brand name off the top of my head but I've seen them at several shops so they are pretty common. They would be way too sheer to wear alone. Over them I use some fake-wool long johns and then regular pants. Add some wool socks and Lake boots and I'm good to -10. I think it's the cycle-short padding that really does the job blocking the wind and insulating you from the seat. I've never had a problem from the waist-down/ankles-up.