Thanks Sparky. I'm no engineer and this is really just a bench racing, so my thinking on this is most likely screwy... Let me add a bit to this because I may or may not be on the losing end of a milkshake bet.
Lets say a guy has a 1932 Ford Coupe, and class rules dictate that streamlining ahead of and including the cowl is allowed, similar to say Competition Coupe and Sedan. Now this ole boy has him a nice flat, nearly vertical windshield and the top has not been chopped. Assume he has made an extended aerodynamic nose, new hood and sides, and removed front fenders. Now he gets to thinking about this thingamajig called a trip fence as described on page 52 (4.CC.10) in the 2014 rule book, and thinks why can't I just put me a little "lip" (trip fence) on the trailing edge of my new hood to help direct the air up and over the windshield. Would our friend be adding a trip fence (which would be allowed by the rules) or is he pushing the limits of what could be defined as a spoiler?