If you think you can't live on 300k with a family in the bay area, then you need a serious reality check.
On a $300k income, even with one earner, you can comfortably afford a $1m+ home (of which there are plenty of single family homes available in many parts of the bay area), and while yes the COL for things like groceries/eating out is higher than in Austin TX, it's not high enough to seriously claim that it's not liveable