Of your three would-be heterodoxies, I believe that 1 and 3 are widely held. As I recall Broughton, she’d agree with them anyway. (As an aside, I doubt your strategy of presuming that Broughton’s reading is the orthodoxy.)

2 seems false to me, because I do not think that there is a unique “the sceptical argument with which Descartes is primarily concerned.” The argument from madness/dreams and the argument from chance/poor design are distinct.

None of that answers your claim that the argument from past failure is a further distinct argument— perhaps it is.

Referring to the argument from sense deception, Cottingham says:

And a page later he says that “Indeed, [Descartes] explicitly asserts that, despite my experience that the senses sometimes deceive, there are many sense-based beliefs about which doubt seems quite unreasonable.”

Why do you think Descartes takes himself to be pointing out that 2 is false? I should go back and check the original texts, but the Cottingham translation doesn’t suggest that reading. Here the relevant sentence.

Yet although the senses deceive us with respect to objects which are very small or in the distance, there are many other beliefs about which doubt is quite impossible, though they are derived from the senses.

I take that to be Descartes lamenting the fact that we can’t, as we should, doubt the fallible senses. To read it as a denial of your premise 2 you have to read the ‘impossible’ there as some kind of normative judgment. (As in, impossible to properly do.) But I don’t see why we should read it that way. One of the themes of Meditation One is that we aren’t very good doubters.

1. The senses have deceived us in the past.
2. We should never trust those who have deceived us even once.
Therefore,
3. We should never trust the senses.

And I go on to say that, immediately after presenting this argument, Descartes himself points out that premise 2 is false. So I guess I agree with your 1 (besides the past failures and the evil demon argument, we also have, in the First Meditation, the argument from origins (I was either created by God or by lesser causes, and in either case I am liable to be radically deceived), the argument from madness (which Descartes also immediately discards, although for no clearly good reason) and, of course, the dreaming argument. I also agree with your 3, actually, except that, in my interpretation, the evil demon is a reminder of what the argument from origins (and not the argument from previous mistakes) taught us, and so I disagree with your 2.