It would be very easy to do... but it's not.
The sdt auto function is strangely coded. There are not general function like "deepthroat" with variables like "speed" that can change with the mode but multiple specific movements like deepSlow deepFast wth constantes. So, if you want a new mode like "hard++", you have to write XX news moves or create the missing general functions.
On the plus side, I work currently on a upgrade of the Custom Automation mod, with possible release this week. This mod allow to create news auto moves with quite a lot of parameters availables :)