Nothing worse than after a good day to see your fish half cooked by the time you get it home, if possible when you are moving between marks gut your fish you have kept on the last drift, if you can take a cool box with you, and if possible get a couple of bags of ice from supermarket, keep your cool box shut all day and the ice will still be solid, if you fillet them put your fillets in between the ice bags, if you don't fillet on board at least see if you can take the heads off them and again put the bodies between your ice bags, normal cool box ice packs are better than nothing but usually don't keep the fish as cool as bags of ice, key is however possible keep the fish cold, even just keeping them in water in your fish box as long as you change it regularly is better than them laying there boiling in the sun!! Hope you have a good trip and the fishing gods are smiling!