Interesting NGE, best tsundere ngl.
Uhm... back to topic I guess :>.
There are ways to unpack tsw2 dlc's .pak files, get the Textures, modify them with e.g. photoshop and reinsert them in an own custom .pak file. This way, any Train of this type will get the changed Textures. You can use uModel or fModel to extract the .pak files, these are not encrypted.
A tutorial which worked on the original TSW can be found here, should still work. I did my retexture of the br182 with it.
If you need further help, just hit me up in my private messages, I _try_ to read them more often.