I do understand your frustration as I've been there before. There's no need to copy the layer. All you need to do is merge it and that will take care...
I did some digging around but couldn't find anything I think in the size you're looking for CUK-series Sholborn, I think is the name of the user, has...
I love airplanes, trains and rockets. I spend my time on the computer 3d modeling, or gaming, and when I'm not on the computer, I'm programming with my calculator!
My favorite addon creators:
Iliosin
GDennish
Trainboi1
EverTrainz
USSc1798