Not sure if this is a bug or not:
I was able to put a cardboard box on Val's back, just like a Portable Container, and load it up, and unload the items, but I couldn't find a way to take the box off her back, other than boarding a ship. Then it just falls to the ground outside.
I'm able to drag a Portable Container back into the Inventory of a Storage Container, but the same action doesn't work with a Cardboard box. Is that by design?