Let's face it, players don't Long Rest unless they feel it is necessary or there is very little incentive to Short Rest instead. If I can Long Rest and regain full health and abilities and spell slots, and it is cheap and easy to do because I get 300+ food supplies before I reach the Grove, and it only costs 40 to Long Rest, why the heck should I Short Rest? What's the benefit of Short Resting at all? Nothing. Nothing at all.
That's my whole point here. We need to make Short Rests worth something so much more than they are currently. They have to have greater value and incentive.
Warlocks, later in the game, still get very few spell slots at a time. They don't even get a 3rd until Level 11. The point of Short Rest = Spell Slot Restore for Warlocks is to provide them with the ability to reset their very limited Spell Slots more frequently than a Wizard or Sorcerer. This gives value to the fact that they reset at Short Rests and not Long, like other classes.
So, Wyll is at Level 8 and casts 2 spells during a battle. It's an epic battle. Wyll is out of spells. Unlike the wizard who could do a lot more spells at Level 10 during a single combat, Wyll is limited by the fact that he only gets 2 Spell Slots per Short Rest. It's HUGELY limiting for a Warlock.
So, let's say Wyll only gets 2 Short Rests period per Long Rest. At the most, that's 6 Spell Slots per Long Rest. 6. That's it. Fighter's Action Surge and Second Wind, which are extremely basic abilities that set them apart from other classes? They can only do each of those 3 times per Long Rest with a 2 Short Rest limitation. 3 times. That's it.
So, compared to other classes like Wizard who can later get so many spell slots per Long Rest and deal much more impactful damage levels, 2 Short Rests only per Long Rest will cripple some of these other classes.
Besides that, the point of more Short Rests is that players will naturally do more Short Rests per day if they can do so without some sort of limitation like only 2 a day. Thus, they will Long Rest less and actually go longer per day than with the current 2 Short Rest limitation. AND if they know ahead of time that Dialogues will be linked to Short or Long Rests, not just Long, and you go to camp when you Short Rest also, then they won't miss out on dialogues and camp events because they'll be going there more frequently to Short Rest. Thus, less likely to miss an event because you are resting more frequently.
As it stands, even in my first playthrough, I tried hard to Long Rest as little as possible because the story is like, "You're gonna turn into a tadpole eventually. The more you Long Rest, the sooner that might happen." So, I was trying hard to not Long Rest. But, with Short Rest limited to 2, that makes NOT Long Resting frequently very difficult. At least with unlimited Short Rests I know I can Short Rest instead and continue on with a single adventuring day for a lot longer.
Now, that said, SOME sort of limitation has to be given to Short Rests or Fighters will ALWAYS use Second Wind and Short Rest and Second Wind and Short Rest until they are fully healed. Thus, it would be broken to not have ANY cost at all to Short Rest.
So fine. Maybe Food Items isn't the best solution. As stated above, Food Management would eventually become astronomically boring and tedious with higher levels of food requirements when you get to higher levels. 200 Camping Supplies would require chests full of random foods like carrots, pies, apples, cucumbers, etc. and would require you to be constantly picking up food and junk throughout the game just so you can ensure that you'll have a Long/Short Rest or two when you need them. That would get REALLY annoying as the numbers increase. As it is, I find gathering all this food hugely un-fun. I mean, maybe at first I liked it, but after awhile of gathering tons and tons of it, you start to feel like, "Geez! I'm REALLY collecting a storehouse of food here. Do I even really need it?"
And the answer is, "No." By mid-EA, you really don't need to collect food anymore, especially with Goodberry and such. So, why? It's true. No matter how much I try to use this system, it just doesn't work.
So, that's why I'm going back to 5e. Hit Dice. It makes the most sense to me and is the simplest. Just implement a Hit Dice system and once your Hit Dice run out for each particular character, that character no longer benefits from a Short Rest.
Fighter at 6th level gets 6 Hit Dice. They could take one Short Rest and use all 6 Hit Dice to recover. They get their abilities back; Action Surge, Second Wind and Superiority Dice. After that, all Hit Dice are used up. If the party Short Rests again, Fighter doesn't get back HP or Action Surge or Second Wind or nothing. Best to manage those Hit Dice better. But, if they only use 1 Hit Dice per Short Rest, the could benefit from 6 Short Rests per Long Rest.
Same with Warlock. Spell Slots restored per Short Rest. 6 Hit Dice. Use them all up at once and that's it. Warlock's done. You traded Spell Slots, basically, for maybe much needed HP. Maybe it was better to use potions to heal up some of that and only use 1 or 2 Hit Dice instead.
As for Long Resting, that's still something I'm trying to figure out a good solution to, but I think a good start is to change the Short Rest system so players will WANT to Short Rest more and Long Rest less. If they know they can heal, gain a lot of abilities back, etc. by short resting, and the only real benefits are for wizards and clerics when it comes to Long Rest, I would think they'd be more inclined to Short Rest. BUT, that's only if there is some sort of Long Rest Cost that makes Short Rest more appealing. That's what I'm trying to figure out here. What should the Long Rest Cost be so that players will say, "Hmmm. Short Rest is much less costly and is still rather effective. I think I'll do that more and Long Rest less."
Then they will actually go a lot longer per game day than they do currently because they can continue to heal and restore abilities without a Long Rest.
