Hi Bob:
The whole issue of the stern light caught me by surprise last week as I was doing some work and realized I had no authoritative information on the configuration of the stern light.
I just did a cross-country move and most of my books are in storage, but I recall that, in 1910, the whole issue of running lights boils down to two categories:
"Primary Lights" (my term) which have explicit legal requirements for size, location, color, range of visibility, and even wick or filament size and orientation to the keel. Examples would be the side and foremast lights.
The other category would be "Secondary Lights" (again my term) that are far less defined, such as the ever-troublesome mainmast light, anchor light, and other portable lights. Some are mandatory, some are discretionary.
Since Cunard ships carried stern lights comparable to the forward-facing lights, I had gotten it into my head that WS would have a similar practice, and that the Cameron prop was just one of many shortcuts. Since the 401 foremast light has been recovered by RMST, and the stbd. 400 sidelight has been sold by Luxury Liner Row, my first reaction was it would have been similar to the existing WS lanterns.
Regardless of the latitude permitted by regulations at the time, what I needed was just a quick reference as to the physical configuration, so thanks again for the image.
Bill Sauder