If camping supplies are a resource that you need for camping. Then craft, find or steal camping supplies.
If the issue is actually long rests then that can be capped. For example at higher difficulties you only get one long rest per level.
I found no areas where I couldn't go to camp. Only allow short rests or no rests in certain areas.
About food again can be reduced or eliminated on higher difficulty settings. I found without looking to hard I had 40+ spare healing potions anyway and hardly used revive scrolls.
Dnd is about resource mgt (hp, spell slots, potions, rests) difficulty settings can affect that greatly
