I'm not sure about this, but I guess maybe somebody in somewhere could have done things that way. As long as they can't fire you based on your appearance, you should be able to do all this stuff. HRT changes would come slowly and maybe people won't notice it straightly, I'm thinking of known people who went under HRT without explaining and people on their environment (those who knew they were born male, i.e. co-wokers, family, etc) just thought they were gay/flamboyant/effeminate guys.
Maybe the most shocking/worrying point could be the implants (and trying to hide them). If you are completely sure they can't fire you for basically "being a dude who completely looks like a chick", then sounds doable to me. Anyway, you have to take into account that unless you're delusional, if you see a woman in the mirror people would see a woman too, so, that's the point, you'll end looking like a chick/butch lesbian/whatever depending upon your style/presentantion, and that would be noticeable for people.
In fact, if you ask me, I think seeing a therapist and then starting HRT could be a reasonably preventive step: as you pointed out, it will prevent further masculinizination and would give you an improved basis on the future.