Valdez ... I have a custom that Mr Rackliff did for me several years ago
Thank You Mr Rackliff
I've been able to easily go 3 nights out (spring/summer & fall) with room to spare. I've carried a full AT setup (boots locked into bindings), bivy gear, climbing rope, split the rack with partners and still have the extra room of the extension sleeve available if needed. Properly stuffed & loaded, it carried surprising well, however I think doing this with the standard waist belt would suck and Randy would be the first to tell you.
If you felt that you needed to stiffen it up a bit, a plastic frame sheet can easily be sandwiched inside the bi-fold back pad.