You might be able to get by with 90k, assuming you're frugal, though given the rents today, it would be wise to live outside the city. 60k would be a pretty crappy existence in SF these days.
I would want them to make a decent wage (much more than 60k in SF) for their hard, essential work. Whether they live in the "community" or not is irrelevant (except for their commute, in which case, yes). It won't lead to better education or a better experience for the children.