I have a gilded chest in my camp supplies specifically for souvenirs. I also use chests for organization in the same camp chest. One for each weapon/armor type that I’m holding onto in case I decide to respec someone later and I need a different aspect on their armor.
Because I don’t want to worry about finding a new backpack every time I just have everyone have 2 backpacks for selling items, then just before I sell I go to everyone’s backpacks and just mark everything as wares. Although, honestly I started doing it because I wasn’t positive that it was giving me the price for the items in the pack and not just the pack itself early on. It’s routine now.