I agree but would take it further: a very aggressive income tax on any non-primary earner in a household that has a total income above 2 or 3 times the median wage. I know there's a lot of "line must go up" types that salivate at the idea of maximizing worker participation rate and GDP, but I think life is probably better when the thumb is put on the scale such that only one breadwinner is encouraged (no matter their gender).