I've been kicking around a packraft specific pack design for a few months. Now that I'm a gimp I can put the time into making a prototype.
My tick list:
-Modular and adaptable drybag harness style pack
-able to handle loads up to 60lbs
-Removable hip belt.
-Removable frame sheet / bivy pad
-2 1/2 lbs normal, 1 1/2 lbs stripped
-very, very non water absorbant
what is out there now:
The WX tex pack - this seemed to be a cool packrafting pack, but its one compartment design with 4 buckles to open the top proved cumbersome. Also the pack lacks any points to strap stuff to the outside.
Next up is the NRS Paragon - This is a cheap solution for kayakers to carry heavy dry bags, or their boat on portages. Its simple, but lacks much shape and I've heard from friends that it can be not so comfey..
Next up was the Ula pack made for the arctic 1000 trip. This seemed to be a good solution, and Ula made a bunch for sale afterwards. The production pack however left a bit to be desired in my book in that the shoulder straps attach to the weak tabs at the bottom of the WXtex dry bags. I've ripped a few of these corners out through normal use, not even using it as part of my back pack. Also, not much protection for the dry bag on bushwacks... seemed expensive too.
So I started the hip belt for a prototype last night... the design I'm working on is closest to the Ula of the three, with more mesh, different suspension and different features all together. Here is the start, pockets upsized from last years ski pack: