_megapixelThey are day packs. No hip belt to speak of to transfer weight to hips. All the weight would be on the shoulders, which is not comfortable at all.
Also, 1 person could do ok for 4 days with 35 liters, assuming there is water along the way. The next person might need a 60 liter pack for those same days. I'm minimalist with ul and tight packing gear. I could thru hike with 32 liters.