Buy bacon, rotisserie chicken, cheese (shredded cheddar is what I buy), peanut butter, fruit preserves, bread, eggs, lettuce, tomato, onion, mayo, butter, fresh fruit of all kinds (apples and bananas especially), milk, juice, vanilla ice cream (this is a must), plain or vanilla yogurt, nuts, cereal, and sugar and/or honey and chocolate sauce, with ziplocs...and preferred junk food (chips) and deli meat or frozen pizza/nuggets if you like them...and of course, your coffee, soda, water beverage park needs

)...
Precook 2 lbs of bacon your 1st night and put in ziplocs in the fridge. Use it to make BLTs, Club sandwiches (chicken with the bacon is sublime), bacon and eggs, and PB, Banana, and Bacon sandwiches (Elvis will be happy). Use the eggs all week to make scrambled eggs, fried eggs, cheesy omelettes, french toast with a fresh banana compote on top, egg salad, etc. Use the bananas in PB/choco/banana smoothies, fresh fruit and juice smoothies, as a fresh fruit brought to the parks, on banana splits, in PB and banana sandwiches, in your yogurt, cut up in your cereal, etc. Use the nuts in your yogurt, as part of a park trail mix, as a topping for peanut butter dipped apples, as a salad topping (if you bought dressing to use on your lettuce/tomato wedge salad

).
We live on different smoothies and different sandwiches with fruit and chips almost all week. When I get back from the parks, I have a smoothie running in 2 minutes so everyone can have something cold that will rehydrate them (and it almost always has banana to get potassium back up). This also takes the edge off appetites and sometimes even fills up the smallest of our appetite folks (who have been known to just have a sliced apple with PB as their "meal" after their smoothie)...
I have used fruit preserves/honey/chocolate syrup/ice cream to sweeten the smoothies and they always have at least 2 fruits or 1 fruit and 1 protein (PB banana with milk and chocolate and lots of ice is a favorite - 3 bananas for one blender-full

)...