I didn't know exactly where this thread would go when I opened it, but I like what's happened so far. There have been many articles written in various hobby magazines, but these are as the individual threads here, expressing an individual opinion.
Here, we are accumulating a very wide spectrum of what constitutes "freelance". Keep it up!
On the subject of modeling a road based on a prototype. To avoid the "look-alike" problem, subtle changes can be made to power, and rolling stock, to give it the "family appearance" of an independant road. Unless, of course, you have chosen to model a "What-if-this-branch-had-been-opened" type of road, which then would look exactly like the base prototype. In this case, matching the power the prototype would have use, in the terrain, and application, would require research, to make it believable.
One exercise that would prove helpful, would be to look at how various roads handled "identical" terrain, and load conditions. Would they all use the same approach?, or was there distinct differences? For a freelance of a "what-if branch" how about using the "prototype-of-a-different-road", that operated in the same kind of terrain/service, for the prototype branch of your choice.
Backstories There is a thread out there somewhere that addressed this issue, with a number of different "reasons" for a road's existance. Backstories can identify the area, topography, materials moved, how they are aquired, and where they are sent. For example, your road might have a large fleet of log cars, because it transships logs from a different gauge rail line, to the ultimate destination, while also handling the coal, or iron, or produce, that occurs within its operating area.
Givens and Druthers apply here, in backstorying what, where, and how.