I tend to blame the founders for this problem. You cannot create a limited-government system that also allows a group to be denied their core federal rights by the underlying entities. Had the founders addressed slavery at the time the Constitution were written, much of the justification for federal expansion of powers would have been nullified right there and then.
Having said that, my own view is that (within the 1787 Constitutional context), the best approach for conservatives in the 1940s and 1950s would have been to have pushed aggressively for voting rights e.g. enforcement of the 15th Amendment. Having said that, it is interesting to note that many GOP consrvatives (including Goldwater!) supported an early version of the 1957 CR act which had tough rules on voting rights. The Act was later watered down by LBJ and the "moderates" and made completely toothless.
If blacks in Mississippi, for example, had had voting rights, they could have defended their rights and the subsequent CR Act which ultimately morphed into the quota monster.