Another, but not very good solution, is to use Vicky's forearm bend dial to remotely control the fix morph in your nightie. That's pretty clunky, though, and not very practical if you're planning on distributing the nightie to others.

Personally I prefer the solution where the nightie is so skimpy that there aren't any arms to worry about! :)  I think that philosophy is partly why 90% of V4 skirts and dresses are minis. Long skirts (and long sleeves) are a pain.