At night, you'll need to store ALL of you food and smellables in the bear box , including your refrigerated items. We bought a small cooler and ice most days. Repurposing a six pack carrier worked well to easily move condiments back and forth from the van kitchen. During the day, I used the dry sink to hold all of our picnic supplies. At night, it all went in a bag in the bear box.
My final bear box tip is to put your smellables in an empty firewood box. People often leave them for the next person in the bear box with newspaper fire starter. The box is a goo way to gather your sunscreen, medications, shower items, etc and protects them from exploding food. We brought a 12 pack of pop up to the mountains and one of the seems broke. A minor mess since we had the box to protect our stuff.