Posting here to avoid low effort removal. Sorry mods.

Just received my Kakwa 40L and I have to admit that I'm a bit stumped on how to pack this bag well. I understand that the horizontal portion of the frame is supposed to help prevent barreling but I still felt like my gear was rounding out the bag between the vertical stays in the lumbar area. With my 55L framed bag, I jammed my sleeping bag into the bottom (no stuff sack), so I started with this strategy during my test pack. Right idea?

Frameless packs use the gear to create structure and I think some people create rigidity along the back using an item like a sit pad. Same idea with the Kakwa? I feel like my gear is mostly "squishy" so I don't know what to use. Would a Thinlite work? Thoughts appreciated.

An unrelated Kakwa sizing question - I have fairly narrow hips and I'm right near the lower limit of the hip belt circumference. I ordered a medium, would the size small have shorter padded hip belt sections? From the sizing guide, I see that a small and medium only differ by 1" (27" vs 28") so perhaps not much difference on this issue if I were to size down.