Template for Custom Post for the EDITOR

You can add custom CSS to the WordPress Admin by creating a new CSS file in your theme called admin.css (for example), and load it in the admin area by adding the following to your theme’s functions.php file:

// Update CSS within in Admin 
function admin_style() {   
  wp_enqueue_style('admin-styles', get_template_directory_uri().'/admin.css'); 
} 

`add_action('admin_enqueue_scripts', 'admin_style');`

(pulled from this tutorial).

I know it’s not exactly what you’re looking for, but you may be able to achieve what you want by hiding some elements and changing layout in CSS.