I'm actually working on one, but there are a few issues I still need to resolve.
-Some of the parts of the head automatically go back to default size. (Top of hair, eyebrows, etc...)
-Causes some alignment issues
-Other stuff
I'm pretty sure that the scaling issue comes from how certain parts get animated, and I don't know anything about animation.
I've attached what I've got so far so you can kinda see the issues I'm running into. It's a very rough version so it only scales properly the first time you run it every time you open the loader. Currently just scales to whatever the body slider is set to. I'll eventually make it so it updates as you scale the body, I just haven't gotten around to that yet.
Haven't worked on it much recently but I'll take another crack at it soon. I'm pretty sure it can be done. I just need to find where in the code these problems are coming from. This is actually a much more complicated mod than it seems like it would be.