What I am trying to achieve is the following tab setup as in the "CoursePress" plugin for WordPress. My idea is to have different tabs for a custom post type, where the main setup tab also has the publish/schedule metabox.
These tabs don't come from WordPress - it's not part of WP GUI.
So if you want to achieve that look, you'll have to implement it by yourself using custom HTML, implementing most of the logic and using
But... It isn't a good idea.
First of all, interface should be consistent. All WP users know how to use native WP editors, and no one is familiar with your idea - it will be inconsistent ;)
Another reason not to implement this design is... Gutenberg - it will be default editor in WP soon and it will cause some major changes in editor layout - so most probably your idea will cause many problems then.