For defalut controller ok. According tou your post I found the Yii::app()->defaultController (returns a string)
but what about default action of default controller? the second link you posted is about an instance of controller (and not of no-nessessary implemented controller)
For answer your question "Any other well-structured approach?", yes, set properties in the controller and check in the layout is a standard procedure.
You better set this properties in a masterclass for controller (like protected/components/controller) in order to be sure that the properties will exist in all controllers that uses the layout.