Working with tiles in Godot can be a bit tedious in a few situations. Fortunately Godot is a reasonably open program, so we can script/extend the interactions without much trouble.
Enter, the godot-tileset-tool-script and it's ever growing set of features.
So far this has been copy-pastaed across my projects and extended by hand. I'm
not sure where it'll land:
I'd like to write unit tests, and extend it to support more tile types
Tilesets should be automagic! But it takes some pre-work and some bitmask learning.
See also: TileSetTools script