Timer would have to start once you found food, since the entire EA map is one big area. So, I would think programming all food throughout the whole map to start spoiling as soon as you land on the beach, all food everywhere would start to go bad. So, spoiling food would only promote long rest. Best not find more food today, or it might spoil.
As for respawns, many have expressed that they hate that idea, and frankly, if you think about it in practice, yeah. I agree. Imagine. You fight the spiders in the whispering depths. But you just can't face her yet. Matriarch, you can just tell, is too tough. So you rest and return. Ugh. Respawned enemies. By the time you get to the matriarch, too weak again. Long rest. Respawned spiders again. It could cause you to basically get stuck in a vicious loop.
Getting attacked while resting sucks. If the enemies are too weak, it's annoying and lame. If too strong, characters die and you reload until you successfully rest. It's just not a good discouragement. It's more annoying than anything.
The idea of LR camp supply cost based on number in camp is that as your camp grows the cost increases. It makes sense from a realistic perspective. Only party members count. Halsin and Volo don't quest, so they can fend for themselves.
