DIY removable frame question.

I did a similar thing with a frameless travel pack I have.

It had a foam pad enclosed within a pocket on the side of the bag that goes against my back. I slit the pocket horzontally, half way up, on the inside of the pack and inserted the inverted U shaped frame. The upper part of the pocket keeps the frame in place.

I don't have my Peak in front of me right now, does it have the velcro to seal in or allow the foam "frame" to be removed like the Jam/pinnacle? if so, I would think that would be a great place to slide any sort of frame into. I would look at delrin rod (available through McMaster-Carr) or potentially a thin Kydex, which could be cut in an X shape (or any shape you want) and has the advantage of being easily thermoformable to your back or specialized shapes. If you are interested in Kydex, I have a size large Peak and some leftover sheets of .08 (on the thicker side) and would be happy to build you something. Maybe I'll whip something up tonight and post it to see what folks think!

Ryan

This might seem odd, but the other day I put a parang (a type of heavy machete) right behind my main pad and it kinda worked as a support. It drastically increased the rigidity of it and help transfer to the hips. So if you ever have something long a sturdy, place it right behind your pad and it will help prevent torso collapse.
@ Ryan, that kydex frame sounds very interesting! How would it compare to your typical removable stays (frame weight, carrying capacity)?