It would be great if we could have a restricted read more like the one in joomla core:
Restricting access to "read more"
From Joomla! Documentation

It can be useful to restrict access to the full article view for not registered visitors and leave just the intro texts readable to public. To restrict access to full article view, do the following:

1. Log in to the Administrator back-end.
2. Go to Content > Article Manager.
3. Set the Access Level for the article with Read More link to Registered ( simply click the Public link in the Access Level column).
4. In the same window click the Parameters icon from the top toolbar.
5. Set the Show Unauthorized Links to Yes and Save the settings. This is a global setting and will apply to all published articles.