When seat shaving, width is, if anything, more important than height. A wide seat forces the legs apart.
The important part to shave width-wise is up near the tank. That's where the rider's pelvis is at a stop. You might even be able to trim a little width off the seat base as well.
That's what I did with my R6 track bike's seat. The front part has been trimmed so that it's no wider than the sub-frame.
For a really good profile in a seat that accommodates short people, look at (and try to emulate) the seat on the current GSX-Rs... (my street bike). Note how the sides are cut in near the front of the saddle, making it narrower.
Contrast this with the R6 front seat. See how much broader the seat is up near the nose?
You wouldn't think such a minor thing would make much of a difference, but it's HUGE.