I've moved with my cats multiple times and shipping as cargo terrifies me. I would never do it. Too many horror stories, completely unfamiliar environment. If you think the cat is scared when you're in the car, imagine when the cat is basically just a piece of luggage. Nope.
Anyway, gabapentin can do wonders. It's not a strong sedative, it's more calming. My cat gets it sometimes just because she gets some attitude. I have found that even though my cat will scream in the car, her plane rides have been very easy. She tends to be a lot less bothered by the plane than the movement of a car. We've moved across country together and though she pitched a fit the entire way to the airport, she was quiet and slept for the flight every time.
I always pack a backpack with all the supplies I might need for her in case she has any accidents. I put a puppy pad in the bottom of her carrier and then a towel over it and if she has any accidents both can just go in the trash. Then I have extras in my backpack. I keep a little bowl for her to drink some water out of and a pouch of food. She's actually never used any of it but I'm always prepared. I actually think cars are just more jarring for them. Anytime I've flown with my cats, someone has always commented they didn't even know there was cat on the plane. I always leave the carrier out for a couple of weeks before the trip and often the cats will just go sleep in it. Make it a familiar place and something that smells like home and it will help a lot.