It's a simple solution/workaround, but a Shortcode could be used. As birgire notedbirgire noted, the whole anchor can be the Shortcode.
And for ease of use, this article has a solution: adding a shortcode button in TinyMCE. You could have a dropdown with a selection of anchors, turning the fight in your favor ;) WP editor is really a PITA when it comes to this kind of characters/entities control.
And the best related Shortcode -> TinyMCE answerShortcode -> TinyMCE answer that I found here at WPSE.