I think you can carry on frozen meats in a cooler, just no frozen liquid obviously. We have found that by taking our mid-sized Polar Bear and 5 or 6 paperback book-sized cooler packs, we only need ice for drinks. We just freeze the cooler packs at night on the trip and properly layer our beer in the Polar Bear when we go ashore. We do this enough over a two week trip that it’s nice to not have to worry about finding and buying so much ice. Clearly, this only makes sense if you go ashore a lot, but it works well for us.