Just to say it because someone might want to believe it: though "ruling king" makes better sense than "rolling," the original was conceivably "Heave way a-rollickin'."

That's "conceivably," which means only that there's a more than infinitesimal chance. How much more, I won't speculate. My feeling is that it's a long shot indeed. I'd think if it happened, it would have been altered to "ruling/rolling king" rather quickly.

If I can think of any other mondegreeny possibilities, I'll let you know.

IIRC, Colcord offers all of Robinson's "Derby Ram" stanzas. If Robinson cooked them up, he was at least as good at bowdlerizing as Hugill! I don't know of any other "DR" texts that compare in the slightest (except, of course, in general grotesquerie).