First of all, thank you for such an erudite essay. I have never seen the issues related to morality treated so clearly and completely nearly so well.

It did make me wonder if you might find interesting a verifiable 'ought from is' that I have developed. It follows from the observation that human beings have no choice but to effect choices [which I got from Warren J. Samuels]. That makes it applicable to any being who appears (physically) to be human who does in fact effect choices (which is, of course, every human being who has ever lived long enough to be weaned). The ethic is ‘mutual respect in effecting choices’ — beginning with respecting the capacity of human beings to choose for themselves whether/how/to what extent to be involved in any way whenever any choice is being effected. If curious to read more about it, a place to start would be "Real Justice (summarized for a '5 min read)'" here in Medium.