Terrain Tool with "don't care"/wildcard terrain type

With the Terrain tool, we specify transitions between different terrain types in order to get smooth borders automatically.

For various reasons, some tilesets don’t contain transitions between concrete terrain types, but only border tiles around a certain terrain type that basically transition into emptyness. This is mostly the case because creating transition combinations between different terrain types takes a long time.

Is it possible to make use of that kind of terrain type using the Terrain tool? I think it would require some kind of “wild card” terrain type where the software basically doesn’t care what the drawn terrain type transitions into. Maybe it’s possible to work around this somehow?

So usually when you do this you will need to use multiple layers to have terrain transitions display correctly. In this case, you don’t really need a “wilcard” but rather a “no terrain here” information, and this is already there. However, support for this “no terrain” still needs improvement in Tiled, especially regarding erasing terrain. This is covered by the following issue:

Do you think this addresses your issue as well? If not maybe you can provide some images to illustrate your situation.