I personally haven't missed camp feature at all. It wasn't really useful at all, and when the AI doesnt need or care about it any immersion value is thrown out of the window. Unless you are talking about VC camps/forts, which then I'm happy they are gone for they were the final nail in the coffin for castles in that mod.
It could have been implemented with fatigue, and also with a nice Raid mechanic
Imagine you see an Army that is encampt at the moment (it takes some time to build up and "destroy" the camp like in a siege), you can then try to sneak up on them, your army starts as one while the enemy forces are scattered around their camp.
You have a unique camp with tents around you, could even combine that with the Tactics skill tree that at a certain point you could learn a perk that gives you wooden walls or Pikes around your camp with 2-3 entrances.
Or giving you the opportunity that while your army in a camp stance that you can send out some troops of yours to go hunting for food.
You know... like in the mods... from roughly 10 years ago... that everyone liked...
That way the camps could have been used offensively and defensively, but all of that is just nothing more than a dream. This thread will end up in the endless space of this forum with no developer reply and the camp mechanic will stay in Warband.