Bagels
Dry cereal. If you want milk on your cereal buy milk at the Café. I like Raisin Bran myself on the train and just eat it dry.
Pita bread
Canned tuna (in water)
I mix the tuna with individual serving mayo & sweet pickle relish packets I've been saving from fast food place visits.
(But, I've seen people use the packets out and available at the Café/lounge on the train too).
Trail mix - mixed nuts, raisins and M&Ms.
Crackers and peanut butter
Hard cheese lasts longer un-refrigerated than soft cheese. Also keep hard cheese in a sturdy ziplock bag.
I don't have any trouble eating 3 day old cheddar, colby, or swiss cheese on backpacking and train trips. Keep the cheese as cool as you can, like wrapped up in a kitchen towel.
Hard salami, particularly it is has the white mold outer cover also works for 3 days if kept in a sturdy ziplock bag.
I pack a cup electric heater to make hot water for tea, hot chocolate, coffee, etc.
Instant Immersion Heater Portable Beverage Warmer Coffee Water
Since there are 4 of you pack a couple cup heaters.
I use a 17 oz metal backpackers cup with a collapsible to heat the water in.
GSI Outdoors 75252 Backpacker Mug
Since there are 4 of you pack a couple cup heaters.