Hip belts with stiff plastic wings that bolts to a framesheet can still be adjusted to fit.    From Wordnik.com.  [Shaister Miester Do Da] Reference

This fall, Osprey is bringing us a stripped down climbers pack that comes in one size and one color - the Mutant 38 (38L) comes with a gorilla grip on the top of the front panel, a convenient clip-in area to stow the hip-belt while you're wearing your harness, and a removable framesheet for use as a bivy pad or a way to save some weight.    From Wordnik.com. Reference