I did just fine in North Texas without a skirt, but I'll be dealing with Montana's winder this year.
Fortunately, a foot or two of snow on the roof will provide some insulation.
I don't know what part of Montana you are looking at, but personally living in an RV when it's 30 below outside is not my idea of fun. Hopefully you can find a partially heated building to park inside of.
Mike and JoAnne
Montana Summer / Arizona Winter
2016 Prism 24G /2002 HitchHiker 38LKTG
ACME EZTowing a 2015 Chevy Sonic RS Hatchback