I will give you credit of originality. I'd never seen anyone dream this one up before.
Was just reviewing some Dealey Plaza film shot the day after the assassination. Looks like the filming was done from atop the Triple Underpass. And what do you know? There is a car coming down the Elm St Ext from the Railroad Yard. It's virtually impossible to see that car unless you are seriously looking for it. Those large trees and shrubs that are on the Knoll side of the Elm St Ext provide a natural "blind".
The car was then parked in the, "NO PARKING At Any Time" zone, back from the corner, and almost directly across from the "wide open" Huge Gates. ALL of this just does not innocently "happen". This was an extremely well planned conspiracy.