Photoshop :: Using Crop Tool To Remove Unused Pixels / Artboard

I have a clipped image that I've placed a drop shadow on (using layer styles) on a transparent background.  I want to quickly use the crop tool to remove any un-used pixels or artboard. 
 
I tried to activate "show the layer edges", but it does not account for the layer style/drop shadow I've placed and also it goes away when you start to use the crop tool itself.  So this doesn't really work.
 
Is there another way to do this?  Other than eyeballing it?  I want the image too be cropped as tightly as possible, but I do not want to tight too tight and cut of the drop shadow.