IMO, it's the only solution, and it's the right solution. The only business the State has in marriage is to recognize its validity under the 1st Amendment - religion alone. But the State should have zero authority in actually validating its existence.
That's why liberals scream over this idea - without the State, what do they have?
The reasons the statists scream over this idea is that they wouldn’t have a way to punish and to keep punishing those who they know will never accept whatever impossibility the state is calling marriage at the time.
Freegards
I think it's a brilliant idea. And I think you're absolutely right.