Custom landscape paint brushes with multiple layers at the same time?

I really wish there was a way to do this. I’ve simplified my terrain drawing for now unfortunately.

When you have 8 or more layers, there’s so much possibility to have complex blends of textures, along with pre-set brushes… yet I still have no idea how.

And I’m really not a fan of automatic painting, because most of that is by elevation, which does nothing in an overhead environment where I purposely want to paint terrain layers in specific places.