I have not flown game meat but have some experience with fish. We froze it and packed it in coolers. No dry ice, but wrapped heavily in paper. It was home in about six hours. I would have felt much more comfortable with dry ice but we had no access to any. Better check with the airline about using it though.
Not all coolers equal so that should be considered. On a Texas hog hunt we realised that we needed one more cooler and wasted a half day wandering around the panhandle looking for one. So, best have the coolers lined up before the hunt.
Have never flown a head, by apparently in AK they clean the skull up and cut it down the middle then tie them together. Another thing to discuss with your airline.
In any case, good luck to you.