I'm stressing. I hated Ruby Moon and think its not worth studying or calling literature. It's cliché, completely overdone, over the top and somewhat shallow.
That being said, my interpretation is this: Ray and Sylvie are characters like the others (Dulcie, Sid, Veronica etc.) being played by actors. It might make more sense to say: If two people wanted to perform the play 'Ruby Moon' the actors would ultimately be playing actors who are putting on a performance of the story in the leather bound book that Sylvie always wants Ray to read to her.
Don't you think that this situation, the content of the play (going down each house of the street, interviewing the neighbours) is a bit like a fable? The flat characters are too flat to have been intended to represent real people. But in a fable, wolves and pigs represent people.
Also, the fact that it's written in such microcosm. "Flaming Tree Grove" is the world to them. Yes, Ray travels on the train to work, but his place of work doesn't really exist.
At the end of the play the actors argue and make fun of the way they've portrayed each character, showing the audience that those characters don't really exist. Then to read the end of the book and close it, thats the play finished. It finished horribly, yes "Don't let it end like that, Ray" (Sylvie) but it has ended, thats the point. it was only a story.
A lot of people i've spoken to think that Cameron is trying to warn us of who's around us. Do you know your neighbours? Do you know the people in your neighbourhood, what might be lurking out there? But, by getting the same two actors to play every neighbour isn't he really saying "it's only you, the paranoia is all in your head". The neighbours that they play are quite strange, eccentric characters, there's no doubt about that, but are they really anything to be worried about? I think what Cameron is trying to say is: its all in your head, and its all just you.
now relating that to my question is hard.