first moss, check to see if you prefer the rucksack close to your back or with a gap between you and the rucksack, i prefer mine close to my back. pjn, i have a lowe alpine 42+10 rucksack and i cant get all my equipment in it for a wild camp, i use my mates vango ( think it is 60 ltrs ). plus i dont like keeping anything strapped to the outside of my bag as i have lost stuff before