I’ve been riding bikes through the winter for 40 years, daily commute, there’s no way of protecting it, I’ve tried everything. Salt will always slowly deteriorate your bike no matter what you do or what you use. Buy a rat bike, cheap older bike, 80’s 90’s trail bikes are good, use them through the winter when the salts on the road, keep your best bike out of the salt. You can use the rat bike for green laning, the more basic the better, easier to maintain, I use XT350 XLR125 in the winter. You won’t lose money on them, I brought the XT for £400 and it’s worth double that now plus it’s been used over 9-10 winters, it’s a win win plus your best bikes stay in good nick.