SCCA Rules help: Spoilers in street prepared

[truegearhead]

I'm working on a spoiler for next season when I enter street prepared class. The rules for a spoiler is "ten inches from bodywork" does the factory spoiler count as body work? Its unclear in the rule book. The cardboard mock up I have goes 10" above the factory spoiler and then drops ten inches and curves around the tail lights. Never exceeding any factory part by 10 inches. My club is pretty relaxed but I'd still like to follow the rule book. I'm going to try and test it out during next week's practice session.