Keeping food out of icewater:
I use plastic strainers upside down in the bottom of the coolers containing food I don’t want sitting in water. One can also put canned beverages in the bottom to elevate the food. You lose some cooler space, and the food won’t be ICE cold, but you save your food! This is particularly handy for produce, which you don’t want super ice-cold, or soggy!
If you are bringing melons, these also make great ‘elevators’ inside the coolers. A watermelon can sit in icewater without dying.
Foodsaver. Yes, expensive, but so is losing your food. We borrow one from a friend. Ziplock bags WILL open if sitting in water too long, plus they keep air inside, which makes it harder to keep the contents cool, and spoils the food faster. Foodsaved bags can sit in icewater all day long without consequence. Consider pre-making as much food as possible!
Soft Coolers: Try small soft coolers inside larger coolers for certain foods you don’t want sitting in ice water, like cheese, lunchmeat, etc.