During past caminos I have seen multitudes of backpacks; usually far too loaded and resembling that of Father Christmas but without any cheery 'ho-ho-ho'. However, one pilgrim with whom I climbed O Cebreiro 2012 in a late November blizzard seemed to have the perfect solution.
He had neither pack nor sleeping bag but simply carried all essentials within 4 sturdy zip-lock bags in his pockets.Two large pockets on a snow-proof jacket contained Crendencial, passport, smartphone/charger, toiletries and a miniscule towel. Two pockets on his snow-proof trousers contained a change of briefs, second set of long underwear, second pair of hiking socks, a silk/polyester bag liner and flip flops. Nothing more was deemed necessary. ...Climbing together through a white-out for more five hours I learned this 'secret' and many more!!