I hear you. Good on you for having a 60L at the ready!
Ok, 56L. One of the below with two 4L detachable side pockets. The sides make great first aid kits.
https://www.fjallraven.com/us/en-us/bags-gear/backpacks-bags/trekking-backpacks/singi-48
https://www.fjallraven.com/us/en-us/bags-gear/backpacks-bags/trekking-backpacks/singi-48
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