Rick,
Sorry, but those back-links are not really practical as user-implemented links. The problem is, behind the scenes, there are multiple HTML documents in use even for a single chapter of the book. To create a link, you need to know which document holds the “anchor”, i.e., the location you want to open. There’s no way for you to know that in advance. The Anchor and Anchor Link User Items manage the complexity associated with intra-book links but the facility that manages the anchors knows the page where the anchor is dropped so it can create the proper link to it when necessary.
You may not need this ability. Most readers have user interface controls that will navigate backwards automatically. So, for example, in calibre, there are “previous page” and “next page” controls (arrows in circles), but there are also “back” and “forward” controls (arrows not in circles) near the top-left of the content window.

The arrows near the top are back and forward, the arrows near the bottom are previous page and next page.
Other readers have similar features, though unfortunately, I am sure some don’t have back and forward.
John Cardinal
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