I don't think so, Rod.
I am not speaking as an authority, so someone correct me if I'm wrong. But if Vernon ever left the country, it hasn't been mentioned in any book I've ever read, so if he did then it is a very little known fact.
Regardless of what I've read or not read, that's very hard for me to imagine. It just doesn't seem like traveling abroad would have appealed to somebody like Vernon (unless it would have been to accompany Elvis), and I don't mean any disrespect by that.