James several of those and jumpers will work.
How do they prevent that cold air reaches your private parts? Of cause the skirts have to be long to prevent that your legs don't get cold to fast, but at the end there is still a very big hole at the end. I think in the past the woman just wear panthose, but I think this is impossible.
Here where I live, we just had the first cold nights. Today I try my first set of custom made underwear made by my mother. I can bring it in place like a diaper and can close it with buttons on the side. To make sure it is not sliding downwards it has its own belt. It took some time to bring it in place. I hope it doesn't make going to the toilet to time consuming. To reduce the risk of making it dirty, I wear a pad between the underwear and the pad. I will report how it is working later.