When I went to Alaska, we went the fish box route, did well with no issues. When I hunted Hawaii last year for Axis, we had all of the meat wrapped, frozen solid, then I ran to a Target or Walmart (can't remember which) and bought 2 soft sided backpack coolers. Brought both as carry ons, had a long flight (Hawaii ---> North Carolina) and had no waste at all. A regular cooler would have worked as well if we wanted to check it (did this for elk in Canada a couple of years ago).