I remember in the US model railroading mags (RMC and MR) years ago, reading of one or two people who built a flat and level layout, and by artfully changing the elevation of the surrounding terrain and by clever use of scenery created the illusion of the right of way passing through the scene being on a grade. The illusion was good enough that unless one actually placed a carpenter's level on the rails, one swore that the track rose and fell.
While I'm sure that maybe one could replicate this in Trainz, I'm not sure that the result would be worth the effort. For one thing, building grades in Trainz is much easier than it is when working with plaster and plastic. For anther thing, I'm not sure that there is enough appearance of visual space in Trainz, to successfully pull off the illusion. The effort is going to be even harder with the build in level reference points provided by the parallel top and bottom of the monitor. It will, at least in my opinion, be fairly trivial to see that the track is parallel with the top or bottom, and that the gradient is in the surrounding terrain.
ns