I'm planning a hiking and photography trip to the Rockies in January as a follow up to a similar trip last year. The major difference in this case is the length of some hikes, with a handful of out-and-backs scraping 25km.
Under normal circumstances, in the summer, I'm able to do 25km with my photo gear (about 20lb), some snacks (usually 2-4lb), and a 2L Platypus/Camelbak bag of water in my backpack without any issues, but I have some concerns following last year's trip.
My major concern is that I won't be able to get to my water easily; though I put the water tube from the Platypus bag into a thermal sleeve, after about an hour the water there would freeze regardless of how often I'd take sips. This wasn't a major obstacle on shorter 10km hikes, but at 20-25k this isn't something I want to run the risk of having to deal with. I also know that winter conditions mean more effort, and that makes water even more crucial.
What are some good ways to retain access to water on longer hikes in cold weather? Does having a life straw in winter conditions make much sense if I'm not expecting much access to water besides snow? Alternatively, are there any good snacks which can fill that role without running the risk of freezing?
To give an idea of size constraints: my current planned backpack for this trip has about 10L of non-camera space plus a 2L pouch for water bags, plus a bunch of generously-sized pockets all around.