Jim Kukula

Ah, looking at your photos more carefully, I see how that rearmost vertical support structure is actually narrower than the two in front of it, so the three vertical supports are not in a common plane. That is really not going to work well with that QL3 support! Maybe you could use the horizontal support of the rack for one of the skeleton attachment loops - at least for the one in the back. That would get rid of the bend in the skeleton, which ought to make the bag fit better.

I don't really understand the advantage of the clip-on backpack straps, whether QL2 or QL3. Either way, you need to haul the straps along somehow, and clipping them on looks awkward. To ride the bike to a trail head and then take a day hike, now that is one application that would seems very suitable for such a system. But to bike to the train or some such, a simple shoulder strap seems easier for carrying the bag off the bike. I guess one could have to walk a mile or two at the other end of the train ride, and then the backpack could be worth the fuss.