This is part of why Google's move to forbid users from installing SSL certificates is so anti-security and anti-privacy: it disables the ability to MITM one's own device in order to observe traffic. I'd support regulation forcing Google to permit users to install our own root CA certs.
Only problem is that you have to explicitly enable the use of custom CA certs in your app, so it won't work with Google apps as you say.
Is there no other way to get at this traffic? Possibly something at the application level, like throwing a debugger at the calls that are originating the telemetry traffic?