Are you an experienced traveler? Are you fit, with good joints?

I just flew on Loganair four months ago, and I felt like I had slipped back several decades. They had stairs for boarding, rather than a ramp, and they had not made things easier by lowering the risers. It was miserable. (I have bad knees.)

How much will your accordion + case weigh? (A Hohner 72-bass weighs 33 pounds, just to get an estimate. Say the case weighs 7. That's 40 pounds.) Better try lowering 40 pounds at home.

Can you get it over the field, up the stairs, into the luggage compartment, back out of the luggage compartment, down the stairs and across the field? When you get to town, you will have to lower it carefully off every curb, because they don't have ramps.

Oh, it would be good to have the instrument on wheels for rolling. Decorate the case to make it distinctive. Why buy foam for padding when you can pack clothes around it? Mostly you want to keep it from shifting around in its case.

Me, I would not take a beloved instrument on a long, complicated trip. There are just too many risks plus too many inconveniences. (Lost, dropped, chilled, overheated, stolen.) Plus big trips have challenges, even if you are enjoying yourself, and another piece of luggage only adds to the challenges.