I am travelling to Lapland on February and I am getting some clothing I need (I live in a warm weather place). I have base layer pants and rain pants already, and I want to buy a pair of pants for mid-layer. Following your guide (https://www.rei.com/learn/expert-advice/layering-basics.html) I see that you recommend the Patagonia Mahnya Fleece Pants as insulated layer. Why I am afraid of, is because these pants are made of cotton mainly... could the excess of heat evacuation could be a problem here?