If you are desperate you can take the neck off and put the body in your hand luggage case and bubble wrap the neck and hold that like a souvenir. I did that with my fretless a couple of months ago and it worked a treat! I have used a box that is 126 x 42 x 15, so well above the allowed dimensions, and it was fine. I have also used Hiscox and other hard cases without an eyelid being batted. On various airlines. I don't think anyone wants to get the tape measure out, they are more worried about weight. I would risk it, smile and feign ignorance!