There is ONE thing I've found that helps when you use a 3-point blower. Keep your head, neck and shoulders WARM. I have two hooded down jackets. Eddie Bauer & Alpine Design. Plus a pair of down mittens. When it was really cold - I'd just stay inside. But if I did go out it was - hooded down jacket, down gloves & down pants. I'd wear a wool stocking cap under the down hood. I have a pair of Karmak(Canadian) pacs I wear in the real cold also.
It left me sort of immobilized but you don't need to much mobility when all you will be doing is sitting on the tractor.
One year I tried my neighbors big cabbed tractor. Not enough air circulation, or something. The windows would steam up and have to be wiped down - every so often. Nice to only need a sweat shirt and jeans though. About the time the job was finished - the window fogging seem to quit. I think, begin with a partially open window and not so much snow on my boots would have helped also. Maybe I just wasn't familiar with the heating/venting system on his tractor.