curved

Hello all, I recently bought a new old stock Stewart RS12 and am planning on stripping and painting the model into Seaboard Air Line. I have done some painting in the past, but nothing that required me to paint curved lines as the Seaboard's switcher scheme has. Here is a picture...

Does anybody have advice on masking curved lines? I have tried pinstripe tape but it doesnt want to stay flat.

Trying to show the distressing done on a few ties just prior to the start of the Curved switch leading to the Serpha Copper & Iron Works and Anglin Oil Works as well as the Noth South Main Line and the Anglin Oil loading facility sideing for more convient loading through the overhead pipe...