One option is to go get an additional MA in Statistics and become really proficient using R. Continue to work on C++ in Machine Learning projects and take a course or two specifically in Machine Learning either from the Statistics department or if they don't offer those courses pick them up as electives from the CS department.

Obviously the other is to continue self-study while working FT using your Ruby development skills and EE credentials.

If it were me, I would just bite the bullet and pick up the second MA degree while supporting myself with freelance Ruby development projects.