As prelude, my major packraft use is an annual trip to a wilderness NZ river, where we helicopter in, walk upstream, find a suitable campsite,fly-fish upstream for the day, packraft back down to camp, and repeat this exercise every 1-2 days, and at the end of the trip, have a full day packraft back to our helicopter pickup.
For this I need a day pack that will allow me to carry a raft and paddle comfortably, plus the normal stuff you need for a day.
This is my “phase 4” model. Made from X-pack nylon, roll top, long side pockets with mesh bottoms to fit my 4 piece paddle, without risk of them falling out, and to allow water drainage, particularly if we stuff a 5 lb trout down them, goretex back, to try to keep my back dry when carrying it. Needs a dry bag inside, as the outer has too many stitch holes in it, and it just isn’t worth trying to seal them.
Weight 340g. About 30cm wide, 20cm deep, and 60-70cm high.
Could also fine tune it to back-country skiing/carrying skis etc.