On this and many other particulars, the evidence of the Founders’ intent is thin or nonexistent. I recall nothing in the Federalist Papers or Madison’s Notes or in other primary contemporary sources to support your absolute prohibition against any delegation of rule making power to executive agencies.
I agree you cannot recall the clear intent of the text of the document or the founders’ intent. An objective reading of their works would reveal their vision for this Republic does not include executive branch agencies creating law.