“Custom Post Type Permalinks” plugin URL strcuture

I managed to find a way to fix this by toying with my Custom Post Type and Taxonomy registrations.

In register_post_type properties:

'rewrite' => array( 'slug' => 'classes' ),

In register_taxonomy properties:

'rewrite' => array( 'slug' => 'classes', 'with_front'=> false ),

I now have a clean structure where http://site.com/classes/ points to the post type archive template, http://site.com/classes/languages/ points to the taxonomy archive template and http://site.com/classes/languages/french/ points to the post template