Perhaps you should think of including a
Page-map or
PageList -- then the eReader will know what page you're on. And the Kindle at least shows the page numbers (if available) on the
active ToC. I don't know about other readers as the only one I have is a Kindle.
You could add the page numbers as regular html in the HTML ToC to correspond to the page numbers you defined in the PageList/Page-map.