The past 2 summers the wife and I have been way less active in the outdoors than we would like since we had our son who is now 2 and we NEED to get out this summer before we get fat and go insane. I am looking for one of those kid backpack things where they ride up on your back/ shoulders . My son is about 34 pounds and 3ish feet tall. Any recommendations ? comfort for me is a must as we use to average 8-12 miles a day so I need a pack that is comfortable.