Extrude depth effect diminishes with perspective

When using the Extrude tool there is currently no way to vary the depth of the effect across a group of objects. Would be great for the specified depth to vary as a function of any perspective that has been applied. For example when you apply a perspective to a piece of text and then add an extrude to this to create a 3D text look. Currently I have to apply individual extrudes to each individual letter to simulate a diminishing depth. With words that contain many letters this becomes a time consuming process. If Corel could find a way to marry these two tools together that would be amazing!