If you're spooling an HT Windlass tippy find some vinyl coated Dacron. I hate the vinyl coated stuff except for my Windlasses. With the spool exposed above the water conventional uncoated line will freeze into an icy unmanageable lump in no time. Wouldn't use the vinyl stuff for anything else due to its inherent stiffness but I do for the wind jobs.
No other kind of coating will save you either, not teflon/PTFE, "waterproofing", whatever. Vinyl is the deal. Woodstock and Mason are two vendors I have used.
Normally the fly line backing suggestion is great, just not for your application.