You can use another player’s campsite. Watch for the Campfire Nearby indicator, sit down for a minute and check the camp’s available objects. You do not have to join their group.
A larger fire does not automatically give more buffs. It creates more spaces; players still have to place objects in them. Each player can add one object.
Upgraded objects keep their original benefit. For example, an Anvil retains the Sharpening Wheel’s Strength benefit while adding an anvil.
Food is another reason to stop. A campfire lets you cook or refresh food while waiting for camp buffs. Forever’s updated crafted foods can provide stat boosts and a small experience benefit, depending on the food.
Legacy perks can improve camping. Currently listed perks include Reagent Economy for tier one camp feature crafting costs, Field Guide for reducing the cooldown on adding camp features, and Permanence for longer lasting benefits gained from resting at a camp.