Just happened pon this board. I quickly looked through this thread and didn't see this idea mentioned.
I've worked ACIS who's kernal make AutoCAD what it is. When you want to use their code they provide the object files for you to link into your code. It preserves their secrets but allows you to make use of the functionality. You could try something like that...
I have an encryption scheme that could further hide functionality, even during execution. [email protected] if I can help.