Your "everyone has access to the rights of marriage" argument breaks down when one considers the types of privileges associated with having a state-marriage. The types of privileges granted to those who are "married" include tax benefits, but also the right to visit incarcerated spouses, to be included in the estate by default, to be considered as a custodian of the spouse's biological children, and other privileges that are specific to the spouse in question.
If the only privileges of marriage were tax benefits and other state provided services I would entirely agree with you. But the privileges that are actually bestowed are inherently related to the specific spouse that you choose. A homosexual couple is denied certain privileges that a heterosexual couple is explicitly granted in terms of access to the spouse's person and property. To say that a homosexual would be eligible for the privileges of state marriage if only they chose a heterosexual partner is blatantly wrong, in that they are not looking for the right to be considered the heterosexual partner of a stranger, but are looking for recognition from the state that they are familiarly related to the homosexual partner of their choosing.
As far as what "Ron and Rand" think that the EP clause means - this just goes to show the lunacy of a monopoly government where the chartering documents are left to interpretation. They think it means one thing, the men and women in robes think it means something else, you think it means a third thing, and I a fourth. But at the end of the day we are all going to be stuck abiding by what someone else thinks without the opportunity of enacting our own interpretation - and thus the market will never be tested, and no one will know if their interpretation was "the best". As far as Ron supporting anti-sodomy laws, my impression was that this was mere posturing against the Federal government's interpretation of the Constitution and not supporting the actual "right" to pass such a law from a libertarian theory point of view. He was, if I recall, saying "The Constitution doesn't give the Federal government the power to dictate to the states, even based on the 14th Amendment". But in my reading of the equal protection clause, it doesn't say anything about race, religion, or sexual orientation. Therefore, from a libertarian POV, it should be read as giving true equal protection to ALL individuals with respect to gov't privileges, services, and recognitions, as long as those individuals haven't instigated force against another. I don't wish to challenge your interpretation of the Constitution, but I am merely explaining my own. As I expressed before, I just wish we each were allowed to associate with our own constitutions so that there would be no arbitrary interpretations to be made, and the most just interpretations would quickly win the support of the rest of the population.