Definitely not trivial, but staged builds are my go-to solution. Depending on the specifics of the tech you're including it can be a lot easier than figuring out how to clean up every little build artifact within a layer - just add a second FROM line and copy precisely the pieces you need in the final image, and nothing else.
I also think it makes the build stage a lot easier to follow for people who aren't as familiar with Dockerfiles and all the quirks that come with optimizing a final image.
