Southern Pacific Switching Layout

[Green_Elite_Cab]

Would CSAO ever operate an isolated spur like the one in my plan?

Or would any other railroad keep an engine at an industrial spur, where the railroad's local would exchange cars of the track leading to the spur, then the engines stationed at the spur would do the switching?

CSAO is almost entirely industrial spurs. It doesn't really have anything resembling a mainline (though it may operate over former mainlines or ones owned by either NS or CSX). CSAO's main purpose is to keep railroads competitive by allowing both CSX and NS to do business in particular areas where it is deemed competition is necessary. This includes New Jersey (Primarily the Port Of New Jersey, but also including branches south), and the Detroit area.

In particular, Southern New Jersey is full of isolated spurs. Many have already been sold to shortlines and such, but there is still a CSAO presence across the state.

Didn't you decide to go back in time though? CSAO is a "new" entity.