Yeah, something like that. I could see one with quick attach buckles that could mount to a pack and if not on your pack, could mount to a bino harness for short hikes.
Has anyone seen a water bladder bag that can attach to the back or side of a pack. An add on bag on the outside of the main bag seems like it might work well. Easy to get to, won’t soak your stuff if it fails and can be removed if not used. Thoughts?
That set-up looks like it will keep the main bag free for all the other essentials. It also leaves the load shelf open for meat pack out. Reminds me of how I used to run my late 80’s era external frame when hiking the Olympics!