AS3 root access

In one of senocular’s AS3 tips ( he mentioned using a TopLevel class which would then be extending by the document class to create “global” root access. Instead of making my document class extend TopLevel, could I assign stage and root properties directly to the document class, from inside the constructor? For example:

package {

    import flash.display.MovieClip;
    public class MyDocumentClass extends MovieClip {

        public static var stage:Stage;
        public static var root:DisplayObject;        

        public function MyDocumentClass() {
            MyDocumentClass.stage = this.stage;
            MyDocumentClass.root = this;

EDIT: Or maybe not define those two properties at all, just reference MyDocumentClass.root from whichever class I need root access too?