I rock the woods with an external pack and am getting ready for my first big hiking forray of a whopping 2 day 50 mile hike. My body is already expressing in painful disbelief that I expect it to carry my heavy pack and I don't even have it fully loaded. I'm trying to trim weight from my pack and thought I would start with one of the big 3 (tent, sleeping bag, and backpack), a sleeping bag.
I now have a zero degree synthetic mummy bag that weighs 5lbs 6 oz with the stuff sack. It's and oldie but goodie and was free. I have read here about down sleeping bags and want to purchase one to save weight and save my hips and shoulders the extra load.
I currently strap my synthetic SB into a stuff sack and cinch to the outside of my external frame underneath the pack.
My question is, that since extra caution and planning should be taken to assure a Down SB stay dry, would it be foolish, perhaps downright deadly, to buy a down SB and continue to secure my sleeper on the outside of my pack?