Remove Custom Post Type Slug but keep category permalink

I have been searching and searching and found two different kind of solutions but unfortunately neither are what I am trying to achieve.

Here is what I would ideally like (note removing the custom post type slug, whilst keeping the cpt categories)

domain/cpt-category/cpt-sub-category/post-name

The two solutions I have found:
1) Remove the CPT slug.
The code provided from this site allows me to create:
domain/postname

2) Using a plugin or this code produces
domain/cpt-basename/cpt-category/postname.

I just can’t figure out how to remove the custom post type slug (basename) and retain the categories in the url. I am now left with perhaps using htaccess to rewrite the url.

Is there another solution to this problem?

Thank you so much for any assistance you can provide me.