From what I have seen, the towing clevices can be either bare metal or oversprayed primarily in whatever disruptive colors that were crew-applied on the vehicle. Evidently, they were rarely oversprayed in the base color of a vehicle at the factory because usually the vehicles were painted before the tools were installed. As far as disruptive colors go, some crews removed the tools before applying the paint, others didn't. Perfect situation for creative license in my book.
From my observations (YMMV), externally mounted fire extinguishers were usually painted the same color as the basecoat, as these were installed prior to painting in most instances. Internal fire extinguishers, on the other hand, were generally left in their natural color which was a gray-green, slightly glossy finish.