Appreciate the reply, but that's worse than what I was doing. M-<right> is not anywhere close to my high frequency areas of finger activity. I've changed all such keybindings.
I notice that C-M-RET is undefined. If anyone wants to add the functionality as described in my original post, and bind it to that key chord, I would be grateful; in the meantime, I'll create a macro / interactive defun to do the same.