I used the eclipse backpack (by Polar Bear) as carry-on last year to bring down 4 meals worth of frozen meats for 8 people. No room for extra ice!
Pulled everything out of the freezer at 4 am and packed on the morning we left.
Pulled everything out of the cooler at 6 am the request of TSA ... repacked....
Pulled everything out of cooler on board at CYOA at 2 pm. Everything still frozen solid.