I use my own little side project (Savory) to track the list. When I come across a page that I don't have the time or energy to finish right now, I save it and add the "reading" tag to it. When I have free time, I can open the reading tag and pick up something new to read.
The best part is that I usually add a couple more tags (e.g. "security" or "economics" etc.) when I save a link. This way, the reading list allows me to filter by topic. It has been an unexpected hack to attack the growing list, since I am usually able to finish multiple articles in a single run, all in the same topic, because there is usually a link between them even when I might have saved them days or weeks apart.
Anyway I like how OP actually has a reading history. I really need to add something similar in Savory. Right now, when I finish reading something, I just remove the "reading" tag and I don't get a neat history.