I was hoping to offer some helpful insight to others, if they are considering the option of the spoiler, I would strongly advise against it if they plan on running boxes, racks, kayaks, ect. There is a potential for interference.
There were no vehicles on the lot that I could have done a test fit with or measured to. If they would have had an Impreza with a spoiler and roof rails, I would have brought my bars, boxes, and racks and done a test fit on the lot with a different car before I placed the deposit on mine. I was forced to rely on the expertise of others, which was the dealer, and it turns out the information that they gave me was incorrect.