I don't see the problem to begin with.
The question with anonymity and data securing always is - "who do you want to protect against?"
No matter how you set up Signal it's not going to help you against intelligence agencies - they'll just hack into your Android or use the available backdoors in your I- or Windows Phone.
Signal is very good (the best?) to encrypt your messages and to sabotage mass surveillance which aims at content analysis. Also not any random bored Data Scientist at WhatsApp will be able to read your stuff.
Controlling your meta-data is absolutely impossible with your day-to-day-smartphone anyway. You'd have to use stolen phones and SIM cards.
In my opinion it ALL comes down to establishing online best practices to keep suspicion-independent mass surveillance at bay. The rest is politics - if your police is super corrupt - they'll just break your fingers until you give them access to what they want.