For some reason the posting system is cropping my posts.

Risking redundancy lets give this another try.

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I have seen this done a few times:

Buy a few inexpensive large stuff sacks. Usually the nylon will be strong enough. Improve them by treating them with a durable water repellent and over-stitching the seams. Stitch a small rubber ball, wad of cloth or sturdy ties into the lower corners. If they don't have double cinch cords install them.

To use you put what you will inside and the top is drawn tight and the cords are looped at the ends and drawn tight over the objects you stitched in earlier.

The result is a simple backpack. The doubled cords don't dig in too bad but you will want to limit the load to something less than twenty pounds. I have day hiked with one of these carrying my rain poncho and liner, jacket and a few other light items without any problems. I carried the water and a few other items on my belt or in a musette bag slung diagonally.

If you willing to get more involved it is pretty simple to stitch in two lengths of 1" webbing and to install a couple of Fastex buckle ends. Giving you a waist belt that will take much of the weight.

I have yet to see it done but it shouldn't be too hard to substitute webbing for the normal cords or to stitch in webbing to create more comfortable shoulder straps.

An advantage to such a modified large stuff sack is that your sleeping bag can ride in one and soft clothing in another. You pretty much need these sacks anyway so slightly modified they serve double duty and keep the weight down. If and when you need a light-duty pack for a side trip or to share the load your covered.

Hint - Kids love to participate and engaged they are less likely to wander off. Setting them up with a simple pack with something light makes them feel like part of the team. Keep the load light because they tire quickly. Even if later in the day you have to carry the load again for a time your better off. And sometimes you find tough kids who will steadfastly carry a significant load for the duration.

To some extent adults can also be manipulated in a similar way. A rescuer, the one with the back and gear, leading victims out has to shepherd everyone themselves. Mount a pack on one of the victims and there is a good chance they stop seeing themselves as a victim. They are participating in their rescue and are more likely to police their own actions and help or guide others. Attitude is often half the battle.