Don t forget that your muscles store only enough glycogen to last 2 hours, hence the typical road marathon runner hits the wall at 18 miles. Total food weight will not be less than 1kg per person per day, inclusive of carbohydrate powder, to achieve the right amount of calories. In either case you will need carrying facilities on the pack to help. Choice of pack. Probably a 30 to 35 litre sac.
Some packs carry either bottles or bladders or both.
The kimm sac original is the lightest but doesn t have bladder facilities. The kimm sac 2 has excellent bladder and bottle facilities besides being more stable on the back. Kimm sac kontour has all the advantages of the kimm sac 2 but is more suitable if you are either a bike rider and or winter activity enthusiast because it can carry Nordic skis and ice axes. It s also got a padded back . This must have a sewn in groundsheet and you ought to be able to find one around 2-2.5 kg easily and the weight is shared.