Sprite padding for pre-trimmed sprite from external tool

Hi, I'm using TexturePacker Importer to create my sprites.
If the sprite is pre-trimmed by TexturePacker, there is no way to assign
the padding of trimmed sprite.

Is there any way to set padding of pre-trimmed sprite?
Maybe SpriteMetaData can have a property call "padding" then we can assign
padding of pre-trimmed sprite manually.

 

Why is this still not an option? It exists for the native sprites, why not for external? This post is 4 years old and nothing has changed.

 

This is simply because there is no API in Unity to set the information.
We could use undocumented APIs but this is something I really don't want to do.