You might think to try using a "Falloff Map" map to control the effect over distance as I did. However, for whatever reason, Mental Ray will not respect this and it still computes the effect over the entire surface. I've even tried using a black and white "Mask" Map to control the physical location of the effect on the surface and this fails also. Below is a sample rendering with this technique. In this case the Black diffuse colored grass is in the foreground and shows what should be the limit of the displacement effect, yet the effect continues on to the horizon as shown with the green colored grass.
I would have to assume that the "View" option in the renderer precludes the use of any other technique that might do the same thing.