Constant problem for me too. I found one winter mask that has nose holes and holes drilled in mouth area, it was better than rest but still fogs. I burned a mouth hole in a buff and that works, until you breathe thru nose or get burnt lips!
anti fog spray from academy check out isle and the thinnest cheapest buff i can find has been working OK lately, but still not great in morninghttps://safishing.com
These are super cheap and thin. they have sales 8 for 25$