Skirting, unfortunately only keeps the wind from blowing right through into your living room. I just received a quote for skirting our 43' 5th wheel yesterday, $5000 cdn. plus $500 for the install and a bunch of rivets in a brand new trailer. NO Way!!!
Our trailer is very well insulated (already had a few nights in the mid twenties last week, furnace didn't break a sweat) but the mercury can easily drop to neg. 35 - 40 in Jan. and Feb., batt insulation and Tyvek housewrap is what we're probably going to do - we'll see, it's not our first winter in the cold but the first in this trailer.
2018 RAM 5500 Laramie CC
Riverstone Legacy 38RE, 960 Watt Solar, 6x6 Volt AGM Battery Bank, Freedom SW 3012 Inv/Charger