A vet-approved, mild tranquilizer wouldn't be a bad thing. If the feline doesn't have an opposite reaction, as shiny mentioned, he'll be a lot more relaxed.
When I moved to CO from LA in 1997, my big red Maine Coon mix was 14 years old. No way I was going to put him through the stress of riding in a moving truck for 12 hours a day. (*I* hated doing it, for that matter.) So I left him with Miss Linda, and she brought him up by plane a couple of weeks later. He'd gotten sick in the meantime, so the plane trip was probably even more of a stressor, but he made it through and was glad to see me.
You can't explain to the cat that everything is going to be fine once you get where you're going. So maybe a little mild Xanax-for-cats isn't a bad idea. You're not drugging the cat for your own convenience, you're doing it to ease the stress on him. That it will reduce your stress is a nice side effect.