When packing food for your backpack cooler, it's essential to choose items that will stay fresh and won't spoil quickly. Good options include sandwiches, fruits and vegetables, hard-boiled eggs, and trail mix. Avoid packing items like mayonnaise or dairy products, as they can spoil quickly in warm temperatures. **RovR RollR, Portable Wheeled Camping Cooler** is an excellent option for a backpack cooler.