The creators of the Kevin Bacon game elaborated on the major rules of the game in their book "Six Degrees of Kevin Bacon". These have been replicated in a number of books including "Six Degrees of Kevin Bacon: The Complete Guide to the Movie Trivia Game"
HOW THIS GAME WORKS
Six Degrees of Kevin Bacon is a movie trivia game where one person who
has been in at least one film is named. Usually (but not always) this
is an actor or actress, but anyone appearing in a film can be named.
This person is then linked to Kevin Bacon using as few films as
possible. However, non-actors and non-actresses that have been in
films, people like Donald Trump and Larry King, usually can be linked
(Donald Trump/54/Neve Campbell/WT/KB Larry King/Mad City/Dustin
Crew members of films don't count unless they also
appear in the film. No animals can be used either, Homo sapiens only.
Appearance in a film by archival footage does not count for game
purposes but extras and people who only do voiceover work in a film do
count. Links are only allowed using films, no made-for-TV movies, no
TV series, no straight-to-video releases, and no video games are
allowed. Actors and actresses who have only appeared on stage, TV
and/or straight-to-video releases and were never in a film cannot be
I've highlighted the relevant passage. Since you were hypothetically an extra in a film starring Bacon, your 'Bacon number' would be 1. Anyone starring in a film alongside you would have a 'Bacon number' of 2.
By comparison, Oliver Stone's 'Bacon number' is 3 since directing (e.g. being part of the crew for) a Bacon movie wouldn't make him a 1, nor would starring alongside him in the made-for-TV film 'Oliver Stone: Inside Out' since it wasn't a feature film. His closest brush is through his work as an extra on the film 'Dave' alongside Sigourney Weaver (whose 'Bacon number' is 2)