Josh,
I also belive that the former SV cabooses were in their original colors. What I learned is that most of the rebuilt cabooses from former C&S box cars were painted "olive drab". But I also have images of box cars with brown colors. What I don't know if the olive drab during some time was only like a dust over the cars. That maybe hard to see today. I inspeced recently a box car who had still his USA letterings in Skagway over box car red / brown colors. There will be still some open points at the WP&YR.
Happy White Pass Railroading
Boerries
[
www.whitepassfan.net]
Here an image of the former C&S box car as WP&YR caboose 909 in international orange colors. More you'll see on my web page at the caboose section.
WHITE PASS CABOOSE SECTION DIRECT LINK. And yes, that's the former D&RGW Rotary on the left!