Hello Emmi,
Thank you for reaching out and I am happy that the CDN functionality in W3 Total Cache works great for you.
Unfortunately, the CDN feature is integrated into the W3 Total Cache, and making a separate plugin for this would be a lot of work.
I understand that you may not need any other caching features, however, you can simply keep all other settings disabled in the W3 Total Cache, using only the CDN feature to serve static assets from the CDN.
I hope this helps!
Thanks!