I cant really understand your motivation...

Obviously, any company interested by someone with a PhD will check at least your subject... and even may have a look at what your work was. So it's not a company requirement to get a job.

So either it's to get a better salary (some companies base their offer on diploma for unexperimented junior)... or it's to pass through some immigration laws (you can work in the country only if you got PhD).

Which one ?

(Anyway, I really think that it's a bad idea: sooner or later you'll be caught... and will lost all that you build)