Using a CustomEditor in the inspector and also seeing normal inspector fields

I want to use OnInspectorGUI() to add custom behavior to my objects (mainly assisting placement and population of objects in the editor), but I also want to be able to see the normal public members inspector for that object (stuff that effects gameplay and the like). I can't seem to find a way to do it, and manually putting in and then assigning every single field in OnInspectorGUI() seems like a really big waste of time.

Is there a way to do this?