If you have the patience for it, I'd like to set aside my position and just examine yours for now. My goal at the moment is just to understand your position better than I do now. I'm not even looking for arguments against it, though I will have questions.
Here's how I understand your position:
(1) The sentences 'Dewey has defeated Truman' and 'I believe Dewey has defeated Truman' mean the same, have the same use.
(Thus Moore's paradox is only an apparent paradox; the speaker who utters 'Dewey has defeated Truman, and I do not believe Dewey has defeated Truman' is uttering a contradiction.)
The idea behind (1) is that 'Dewey has defeated Truman' is really 'I believe that Dewey has defeated Truman' but elides or suppresses the 'I believe ...' It is nevertheless an expression of belief, or of purported belief, if we have to account for insincerity at some point.
This is so because we can only talk about the world as we understand it, and we understand it entirely in terms provided us by the mental model of the world our brain constructs and continually updates.
Our words refer to artifacts of this model, not to objects in the world.
Everything we say is, in a sense, a 'report' on the latest iteration of the model we are aware of.
If I have this right so far, this is where I'm a little unsure. Certainly, as you've said, there are those occasions where we might speak about our beliefs as an outsider would, observing ourselves as an object, but this is not the usual case, so 'report' there sounds a little wrong. We want a clear way of saying that the sentences we utter are informed by the mental model, entirely dependent on it, but for speech acts to be something other than comments about it.
Certainly we'll continue from here with a pragmatist account of speech acts, but we have to backtrack a little because 'belief' is being used in two ways here. On the one hand, it's kind of kind of pragmatist shorthand -- 'Jim believes there's beer in the fridge' just unifies descriptions of actions Jim is taking or might take, things he says or won't say, and so on. A belief is nearly a theoretical posit -- what we're really interested in is behavior. But above we claim that 'Dewey has defeated Truman' is something a lot like a description of my mental state, that it's about my beliefs in a sense not too different from the way people generally understand beliefs, just somewhat broader. That claim doesn't seem to rely directly on some idea of utility as a pragmatist account might; it's an argument about what the semantic content of our speech acts must be.
So my question is roughly this: do we argue here that the pragmatist account actually kicks in a little earlier, in the model taken as a sort of Bayesian inference engine, that this is where we find the idea of utility? But then are we also looking for pragmatist account of semantics? Do we even need one, or do we sort of get it for free by focusing on how the model (whence all our speech acts originate) works?
Not too clear, but I hope you get the gist of what I'm asking. If not I'll take another run at it.