Well, usually I travel during the day, while they sleep, and put them in the carrier with some juicy fruits. But mine travel fairly well, they just sleep all day without waking up.
My male, Loki, is like your George in that he is very adept with zippers, but he has never been able to open the carrier's zipper; I think it is because it is too big for him, so yours should be fine as well.
If it is a long trip, you may want to stop from time to time to check on them, specially if they are the type that wake up during the day. You can offer them water at those stops.
This may sound obvious, but make sure they have their sleeping pouch (a dirty one that already have their scent) in the carrier with them, that should help in keeping them calm.
Hope there's someone else with more suggestions.