My mother traveled with her violin recently, and the FA proactively asked if she could put it in the closet to keep it safe. C+ would be a good buy, but I think that FAs are pretty mindful of instruments and do what they can to ensure its safety, so I wouldn't be worried. Check the aircraft layouts for the equipment to ensure that the aircraft have closets (not necessarily on the TATL segment, but if there are any domestic segments involved).