Thanks for all of the comments. It's a tricky issue. The goal is absolutely not to sedate him and he hasn't appeared even the least bit sedated with any dose so far but I'll definitely stick to the lower end. The idea is just to help him be a little less distressed. It's not a crate issue - he's fine with that. He's just very tightly wound and new/unusual situations with lots of noises and commotion really upset him. No airline employee will think he's sedated - probably the opposite.
I wanted to report back on traveling with a dog and Xanax. He had one pill about 4 hours before the flight and, while anything but sedated, was slightly less crazy/hyper/whiny than he would usually be. Everything went fine and he was really happy to see me on the other end.