I'd like to see a "cargo expander" for the player's inventory too.
We have perks/mods that help with encumbrance, but nothing that increases total slots.
I don't think a perk would be appropriate, but a series of bags/backpacks might be nice.
That would be useful. This is one of the reasons why I play without traders. The inventory is small, and if you collect everything to sell to a trader, it fills up very quickly. Then you either have to constantly dump everything into a chest or manage your backpack and give up cheaper or less necessary items.