Are you chartering? If so, from whom?

The reason I ask is because TMM has a Martin guitar they rent to clients. I doubt they would rent it to anyone who is chartering from another company though, but it's worth calling them and asking.

Otherwise, I'm afraid I don't have a good solution for you. Delicate luggage is not likely to fare well if checked through ... and as far as I know, "smaller" carriers often insist that you check your luggage. I know I was rather ticked off when LIAT made me check my carry on which is small enough to go under a standard airline seat.

The whole [color:"red"]point[/color] of packing using a carry on bag only is so you don't have to worry about lost or damaged luggage! Having to check your carry on pretty much defeats that goal.

Hopefully, someone else will have a better solution. Sorry.