There is magic in this game therefore Magic bags of holding, and other magic carrying devices. That should be written in to help deal with the massive inventory.
That said, Carrying around barrels of oil is just stupid. The reason this game is so much better then Divinity is its not all cartoony and kid like, it tries to keep a base in a real universe, something that people can imagine and believe they are there.
Once you get into extreme cartoon land you lose that feeling. All the back and forth extreme examples tossed on one side or the other, aside, all the OP is saying is can we keep this game grounded and not "lose" it in extreme fantasy and bugs bunny cartoon stuff.
And I could not agree more.