This is long, so here's the Summary of it with a deeper explanation after:
1. Allow unlimited Short Rests. To Short Rest, you must Fast Travel to Camp and click on a bedroll.
2. Short Rest allows Hit Dice use. Once Hit Dice are gone, no HP recovery per rest.
3. Abilities and Warlock Spell Slots, etc. are ONLY reset IF at least 1 Hit Die is used during a Short Rest for each character (meaning, if Lae'zel uses a Hit Die, her abilities are reset, but if Wyll doesn't, his spell slots are not reset). Didn't use a Hit Die? No ability or spell slot reset.
4. Arcane Recovery only able to be used during Short Rest, and reminder to use it would be nice.
5. Dialogues tied to Short AND Long Rests, and characters transported to camp when Short Rest also for dialogues and to show you ain't just healing somehow on the fly. You are pausing your adventure to rest.
6. Long Rest Locations must be unlocked.
7. Restrict Fast Travel until a Waypoint is at least found.
8. Get rid of camping supplies altogether, and food, and drink and everything having to do with Camping Supplies.
9. Time-Sensitive Consequences.
10. Auto-Save occurs just before a Time-Sensitive Encounter occurs so you can always reload to that Auto-Save if you didn't mean to trigger the Encounter. A Warning notifies you that you are about to trigger a Time-Sensitive Encounter, so you know that if you care, you'd better do it now. If you don't care, ignore it and move on or turn back. Plain and simple.
11. The game should warn you if you try to rest and it's restricted with a "Are you sure you want to Long (or Short, as the case may be - like with Waukeen's Rest) Rest here? This will end the Time-Sensitive Encounter and may have negative consequences."
12. Unlimited Long Rests when it is not a Time-Sensitive Encounter.
OK. I know I'm all over the place, back and forth and all, but I'm just trying to work through this.
I can't help but agree that Food is useless. It's a terrible way to limit Short or Long Rests. It seems to keep coming back to this. For Short Rests, either the cost is too steep or not steep enough to stop Fighters from spamming Short Rest and Second Wind and healing to full each and every fight. Likewise, there's nothing preventing Warlocks from spamming Short Rest to recover infinite spell slots.
The same is true for Long Rests. Either the costs are too high or not high enough to prevent Long Rest spamming, and if you go with the "Higher Levels Require More Camping Supplies" thing, you'll have to keep track of so much food and crap that it'll be overwhelming your stores at camp. Or, as mentioned by Fuji, you'll later have so much gold that you can just buy an infinite amount of food and never have to worry about it.
So, again, why not Long Rest after every fight instead of Short Rest? If you can afford to buy 5,000 Camping Supplies and store them at camp, it wouldn't matter how much it costs. AND, if there are no other repercussions, like the Hag kills Mayrina, or the counselor dies by being burned up in Waukeen's Rest, or the druids finish their ritual and kick everybody out, then why bother with Short Rests at all? If I can just spam Long Rest without consequences, why Short Rest at all?
So, here's another potential solution for Long Rest (the longer version of what I summarized above (cutting out things that are simply repeated):