If you are comfortable on long trips without the stays-only you can decide that. I need those stays because my shoulders are so pressure-sensitive that I have to transfer as much weight as possible to my hip belt. Some folks can do without stays and a hip belt, but I'm definitely not one of those--even my day pack has to have a hip belt!

Maybe remove the stays but take them with you to see what happens?
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May your trails be crooked, winding, lonesome, dangerous, leading to the most amazing view--E. Abbey