I don't know if I would say that it wouldn't stretch the commerce clause "even a little bit."
If you read the language of the commerce clause, it reads "to regulate commerce . . . among the several states...." This could easily be read to mean only transactions between states could be regulated. This interpretation would mesh with some of the problems that the states had under the Articles of Confederation.
But, even leaving that aside, your interpretation gets us where we are now--a system in which, as you admit, is a National Government that has de facto unlimited powers to regulate as it so chooses. There is no question that was not the intent of the Founders, and it strikes this writer as strange that we would interpret a clause of the constitution to reach a result that we KNOW is directly contrary to that envisioned by the Founders, especially when a perfectly legitimate reading of the document is available and comes much, much closer to meshing with the intention of the Founders and the document.
Unlike others on this thread, I don't feel that the meaning of every clause in the constitution is plainly obvious, but to read a clause to mean something so directly contrary to what it was intended to mean just is unfathomable to me.