OwlGreen
Hello, I would like to suggest you the method I use myself.
I'm assuming you have installed the amazon s3 library and set your fof upload settings as stated.
Create a bunnycdn account and point cdn.yourdomain.com to your current s3 address as s3.amazonaws.com/bucket/. Then point cdn.yourdomain.com as cname to the bunnycdn subdomain. After performing these operations, use cdn.yourdomain.com as a special prefix in the fof upload settings. In this way, the files will be hosted on the s3 and presented to the user with a special cdn. It works tremendously.