Just got my Clutch FX Pants from Up North Sports...They seem well made and should be warm...used to having uninsulated shells and it will be nice to just throw these and go...no layering. They also have F.A.S.T insulation so I’ll float!
https://www.upnorthsports.com/snowmobile/snowmobile-clothing/snowmobile-bibs-pants/mens-bibs-pants/fxr-clutch-fx-pant.html