Configure Google Voice/Hangouts to work like T-Mobile's wifi calling?

I have a Google Voice number, and I have Hangouts on my phone.

What I would like to do is forward my Google Voice number to my "real" phone number when I'm in range of a cellular network, but answer it in the Hangouts app when I only have access to wifi. Effectively identical to how the "wifi calling" feature works on T-mobile.

Right now, I've got Google Voice configured to forward calls to my real number, and I've also got the Hangouts option checked to receive incoming calls. But when I call my GV number, my phone rings in 2 different applications simultaneously on the same device (dialer and hangouts) and I have to choose which one to answer, which is less than ideal.

Is there any way to configure Hangouts to only notify of incoming calls if my actual phone isn't already ringing? Or a way to automatically toggle "answer incoming calls" on and off depending on my data connection (maybe with something like Tasker)?