I was able to find these 4 news articles concerning Valentine Sally, but they are all from another forum and I was unable to directly source them. I'm assuming the last article listed here was run on an anniversary of her discovery but someone listed it as being run on February 4, 1982 (it must have been run in 1988 or later, as it references events from 1987).
This is the first I've ever heard of her traveling with two truck drivers instead of one. Wouldn't the cab have been too crowded?
I also assumed the sketch was based on an interview with the waitress, but it sounds as it was completed first and then the waitress came forward.