Good writeup, and the downside you flagged is the interesting bit. Profiles are enumerable. A dummy profile survives a glance at the screen and stops working the second someone can see profile 2 exists and asks you to open it.

The property you want on top of your setup is that the second thing can't be shown to exist at all, so it looks like random noise rather than a locked door. Then the dummy isn't a dummy, it's just the phone.

(I work on DeniableOS, which is built around that. Your profile setup is still the right free answer for most people and I wouldn't talk anyone out of it.)