OK, KotC faced the same issue just about every cRPG has to face--resting and its implications. To summarize the situation:
1. If you allow resting at any location, players can simply rest after every fight and resources become meaningless between fights. Attrition just doesn't work at all. The "solution" of allowing PCs to be attacked while resting *encourages* you to rest after each encounter, while you're still strong enough to deal with a random encounter; if you wait until the party REALLY needs to rest, a random encounter will kill you.
2. If you disallow resting over an extended period, encounters become progressively harder as the PCs use their resources. While there are work-arounds (especially with Enchant Wand), the attrition can be a real problem, especially if it leads up to a major end battle with the party lacking needed resources to win and unable to rest to regain them. Potentially a save-game killer, too.
3. If you limit resting somewhat, as KotC does, then 1 or 2 apply alternately with the additional sting that after every fight, the PCs have to travel to the nearest rest site to recover. KotC discourages this practice somewhat through spawning random encounters after the rest which must be fought for the PCs to get back to where they started. It's possible (and more fun) to play through multiple fights before resting. But since the party could POTENTIALLY rest after every encounter in most game areas, once a campfire is available to them, encounter design has to take that into account in order to be challenging. That discourages simply pressing on and not resting as often, because if the encounters are calibrated to a fully rested party and not an attrited party, the party that doesn't rest will be harder-pressed (fewer resources and up against a harder encounter).
There's a potential work-around available by adding timed events to the game (you have X days to get back to save the town from giant attack), but these events tend to screw players who dawdle despite the urgency. Allowing resting once every "8 hours" is useless as the player can simply "pass time" or, in worst cases, let the game sit for a few hours or walk back and forth in an explored area. Boring and unhelpful.
So, I'd like to propose a change to the resting procedure for KotC 2. Introduce the idea that campsites can only be used a limited number of times. Make the limit known immediately. For example, a secure chamber in a fortress might work as a resting spot for 3 rests, after which time enemies break down the door and the campsite is no longer safe (removed from the map). A site could have a limit of 0, meaning that it can always be used. A site with a limit of 3 rests, for instance, would discourage the "rest after every fight" syndrome and reward players who can win fights without burning lots of resources, while still allowing resource recovery if sorely needed. This change would allow adventure designers to plan for a certain amount of resource usage over the course of an adventure and would add another strategic consideration to challenge players.