Yeah that "halfway to the cabin" part is the WORST. It's not just the belt, it's the whole situation. You're stuck in the cold, probably far from your tools, and now your whole trip is messed up. That's why I started throwing a spare belt in my backpack every single time. It takes up no space and it saves the day. Learned that lesson the hard way after a long, cold walk myself.
Carrying a spare belt is smart, but what about the drive belt tensioner? Mine failed once and a spare belt did nothing. Now I check that plastic arm for cracks before every trip.