One way to get around this in some cases is to subscribe to the feed's associated email newsletter, which, IME, is more likely to have the full text of the article. This, of course, introduces other problems[1], but if your goal is to remove reasons to habitually look at your phone, it's worth investigating.

[1] The feed needs to have a newsletter in the first place, you probably need to clean up the markdown a bit before shoving it into an epub (I've noticed that table-based layouts are much more common, for instance), and your email provider probably doesn't provide an RSS feed of your inbox. The latter two are straightforward to fix but do require a bit of programming elbow grease.