Pretty easy to do with some work. Remove the staples from the seat pan to remove the cover. Mark the area you want to remove. Take an electric knife or a bread kife cut along your lines you drew. Use an electric angle grinder with a 80 or 100 grit sandpaper disc to smooth up and shape the rough spots. Once your satified with the shape and the look. Put the cover back on using a hand or electric staple gun, staple the cover back on the seat pan.
I to am vertically challenged and have done this on a many of my offroad bikes as well as making "custom" seats for my street bikes.