It's been a while since I read anyone doing it but I seem to recall that you are correct, it would give you all the RSNs and the pro local sports gams on your RSN.
I recall reading someone doing it with Entertainment or Select with Sports Pack, but I see no reason that Family would be any different, as none of those packages come with RSNs.
For the other poster, DirecTV does offer a $29.99 month family package, though they do not advertise it, it is only available by request from a CSR. We have a list of the channels in that package on the sticky at the top of the DirecTV forum.