Just a recommendation from backpacking when I was younger but you might want to make your frame focus the weight on your hips and not your shoulders. especially if you're going to be wearing this for a while.
Might even be able to re-purpose and old external frame backpack. https://www.rei.com/learn/expert-advice/backpacks-adjusting-fit.html
Might even be able to re-purpose and old external frame backpack. https://www.rei.com/learn/expert-advice/backpacks-adjusting-fit.html