As far as women of color, any color, went it was automatically easier to get away with this type of crime. Free or not. The miners in California always formed squaw hunting parties, the objective being to take as many Indian women as they could and keep them. This usually involved killing the men trying to protect them and stealing the children as it was legal to obtain a kid for labor by killing the parents. You could collect the bounty, too. The slave had at least the pretense of some type of protection with the legal system - slave rape was against the law - but getting the rapist charged and convicted was nearly impossible. At best, your owner could sue for damage to his property. There was also the idiot notion, very prevalent then and for some time further into the next century, that women of color were loose anyway. One of the several lynchings that took place in mining towns was one in Downieville, where a Mexican woman stabbed her rapist and was hung for defending herself. Apparently, self-defense was not applicable to her because somehow she 'invited' it by living alone.