This is an area where you and I agree, abortion is a moral issue and morality cannot and should not be defined by the government. Government should provide for the common good and protect our rights. Some would argue that having laws against killing or stealing is legislating morality but I look at it more as a public safety and private property rights issues.
But… you did not mention laws that have been enacted where you can be convicted of 2 murders if you kill a pregnant woman (such as Lacy Peterson, for example). Scott Peterson was convicted on 2 counts of murder. This seems to offer a bit of a challenge to your argument as to drawing a “bright line” of “personhood.”