Packing wedding dress for flight

Hi I have seen many people answer this question plenty of times, but I am still confused. People are saying that you can hang your wedding dress in the closet in the plane if you ask and use it as your carry on. Well, I checked with my airline and they said they would do that, but the garment bag has to be 50" in length. It's more like 60". Soooo. I have no clue how I am going to pack my dress. And some people say something about a foldable garment bag onlind, but I can't buy one because we are leaving in 2 days. Why don't they just allow you to take a regular wedding dress garment bag?