- Agree with no short rest limit.
- Disagree with the "healing recovery" button. Hit dices are not more complicated but way more interresting.
About supplies you're overcomplicating things once again.
Resting require supply bags (apples, sausages and other food as supplies ON/OFF) + small chance of unexpected encounters in dangerous area (mini camps) + small chance of unexpected events at camp (main camps) = perfect system.
You're welcome

On a higher level, I wants stronger enemies with better stats and skills, and if possible, I wants them to be smarter. I don't want to increase the difficulty level by food problems.
Totally agree.
The idea of the HP Recovery Button per character is similar to Hit Dice, but the difference is no roll and thus no RNG with it. The more I thought about it, the more I said to myself, "You know. I could see a lot of non-D&Ders being really put out if they take an SR and click on the HP Recovery button and only get 1 HP back because their character has no Con bonus and they rolled a 1. Whereas, a character with Hit Dice of 1d8 with no Con bonus would at least get 5 HP back per button press. I figured, once again, it could be a difference in Difficulty settings. Core 5e mechanics difficulty = Hit Dice at its finest. Easy Mode = HP Recovery Button. Something like that.
I don't disagree with this necessarily: Resting require supply bags (apples, sausages and other food as supplies ON/OFF) + small chance of unexpected encounters in dangerous area (mini camps) + small chance of unexpected events at camp (main camps) = perfect system.
The issue with that, though, is it would require a considerable amount of work, and there seem to be so many resistant to unexpected encounters anywhere. The system I'm suggesting here, however, wouldn't. It's more of a psychological deterrent to spamming either Long or Short Rest. It's something Larian could control.
And if food spoils, that makes each one even a bit more limited. Spoiling food also, again, provides more meaning and purpose for the Survival skill.
What I like about the food spoiling/ preservation system is that it prevents players from hording over 1,000 camping supplies. It keeps the camping supplies numbers more controlled and minimal.
That said, perhaps buying Camp Supply Packs from vendors wouldn't be good. Then you'd have more packs to craft more camp supply packs with. This would defeat the purpose of the preservation system. Maybe vendors just sell food and not packs. This would do several things. First, backpacks would be a much more precious commodity in the game instead of simple item management tools. Second, like I said, it limits just how much total camping supplies you actually can have at one time. Thus, it promotes less frequent long rests. Third, vendors could each be stocked with variable amounts of food each day. Again, this could also, then, be different based on difficulty settings. Anyway, the point is that it would provide more limits to just how much food you can actually have at one time. And finally, it would be slightly more annoying to buy food. Thus, again, imposing a psychological discouragement from spamming long rests. If I use too many long rests and have to go to a vendor and buy 60 camping supplies worth of food - hopefully I can - in order to just long rest, that's going to make me reconsider this approach. Maybe I'll push myself more and long rest less so I don't have to buy food from the merchants. However, if I'm really not doing well in the game, then it won't matter how annoying it is to buy separate food from the vendors. I'll do it anyway because I have to.