Check this photo.
I use an old 45 Lt north face pack. I have been using this set up for decades and is good if the trail is wide enough for up to 5 km in then I find the trails start to get thin. .
No fish cat though ( I found them to heavy ) I have a Cumberland , Togiak & JW Stillwater The Tagiak being the best
I clip it to my pack. None have ever been deflated.