I've been an idealist. I understand all the arguments. The base fallacy at the heart of all this is the one I mentioned.

On the very last point: the conclusion that consciousness is thin, like a photograph, and the world thick -- follows from the most complete explanatory account of how consiousness works. The idea that there is no world, or that the world is a thin transcendental ego -- this abandons the project of offering an account of consiousness at all and ends up in incoherence.

Within consiousness I am presented with: what I cannot change (fixed perceptions), what I can change (eg., imagined perceptions). This duality is immanent to consiousness itself. The imagination can apprenend the fixed, ie., I can imagine scenarios that I could, in principle, see. So there is, immanent to consiousness already, a representational duality: I have both fixed perceptions that I cannot change, I have mutable perceptions (imaginations) that I can -- and my mutable perceptions are representations of my fixed perceptions.

All of the dynamics of the duality of the represented and representation, of the fixed/external and of the mutable/internal -- are already immanent to consiousness.

What remains to be explained is: why? The obvious answer is that the reason i have fixed perceptions is because they are caused by a world that they depict, and the reason I have variable/mutable perceptions is they are caused by me as I represent that world to myself. The duality immanent to consiousness is explained by the duality of the measured and measuring.

Even if you abandoned the world "external" and replace it with "fixed", you gain nothing. Everything which seems objectionable about this duality is already present. If you simply assert it, rather than explain it, your position is weaker because you've nothing to say.

The causal origin of our fixed perceptions is the world, which impacts our sensory organs, interacts with our bodies, and produces a thin perceptual surface to us which causally-directly depicts the world that we are in. These fixed perceptions are constructed by our bodies thru this process of activation, which we can call "measurement with post processing" ie., a kind of digital camera rather than a chemical one.

But in any case, to answer your final question: yes, the difference is that "consiousness" with this duality of the fixed and the variable, and their representational relationship, only makes sense if part of consciousness isnt being determined by consciousness. The need to say what determine it means the "consiousness is complete" option incoherent, if "consciouness" as a term comes to adopt all the properties it needs to explain the fixed perceptions, then you'll find consiousness becomes both the material and the mental -- and all you have done is empty the word of all its meaning