Glad IK&P is useful, snowshoe. It could do with a darn good tidy up but it's too far gone now.
Sounds like you could use a pack then. I actually thought my Tatonka Lax
https://apaddleinmypack.wordpress.com/2 ... xe-review/might have worked well with some wheels added to the frame.
Those sort of L frame packframes are quite common is North American hunting shops.
That bag you linked to looks a lot like the Ortlieb I mentioned.
The key, as you may know, is having some rigidity between the shoulder and hip mounting points to enable weight to rest on the big padded hip belt, not hanging off your shoulders. Otherwise, a lot will depend how tightly you can manage to pack it, but 115L of volume is a lot of stuff to carry!
I wonder if the expensive SealLine Pro Pack RE on that same page actually features a rigid back panel?
If not, up to a point I have found that the friction between the bag's fabric and what's you're wearing on your back can help support the load. My 'canvasy' Watershed UDB is good for that but has a terrible harness.
Because I love my UDB but not its cheap harness, last year I used an NRS Paragon pack harness
https://apaddleinmypack.wordpress.com/2 ... ss-review/while hiking with my packraft in Turkey. The holding straps could handle a 200-l bag, but I felt 25kg was the limit (for a 2-week walk). the good thing with a pack harness is you can wrap the Sunny in there for a day paddle, or whatever you like for longer trips.
Not looked at it for years but I learned a lot from the brilliant BP website back when I first got into IKs. They were always big fans of the Sunny which they used to import direct before Innova finally took them on.
If you're a hand pump fan, I can recommend the K-Pump Mini. That's what I use when travelling with my Gumboat. Will take you 10 mins to do a Sunny, and more compact than a Bravo.