I mentioned in a thread somewhere the idea of a "strict carry weight" option but this would most likely be part of an immersion mod. The inventory slots do feel like they are unlimited with the exception of barrels, as you said. Players could still enforce a strict carry limit upon themselves (role-play it out) and not load up the inventory past a certain number of items or weight.
An idea suggested in this thread:
So, in other words, let's say they restrict Send to Camp to Waypoints. You have to physically go to a Fast Travel point to Fast Travel or Send to Camp. That at least provides purpose to Encumbrance.
