I'll just offer my initial thoughts.

The dual purpose idea is great but sleeping on the ground isn't usually a big deal. I would suggest instead of a cot either shelter supports/tent poles or even a chair. Maybe get creative and create a toilet seat for those who prefer not to squat.

I don't know much about carbon fiber durability so maybe these questions aren't very good. How does it hold up to cold? People use their packs in below freezing weather. Also, I've read that some carbon fiber items can be brittle. Will the frame break if dropped?

Why would people want an external frame? I still like mine, but I'm weird. Marketing such an item might prove the biggest challenge.