Dear Erik,
please, don't apologize for being critical---if the idea is to have any chance at all, it must be able to withstand some pressure. So every issue you point out is helping me, and I'm grateful for having the opportunity of discussing my idea.
Regarding the problem you see, do you think that narrow content is just in principle not capable of solving the problem of reference, or do you think that if one believes in narrow content at all, then there's really no additional problem left to solve---i.e. that one then is committed to a kind of eliminativist stance?
To me, the problem to solve is how any sort of mental state refers at all---i.e. how it comes to have any kind of content. For instance, I disagree with the idea that a thermostat refers, simply by virtue of being in a particular state, to the temperature (or to its being 'too low' or 'too high'). There's no salient difference between that thermostat and any other system with two possible states---it will always depend on the environment which state the system is in, and thus, the representational content could at most be 'I am in the state I am when the environment dictates that I evolve into this state'---which is basically empty, and doesn't really say more than that the system is in one of two possible states.
Reference, semantic content, etc., needs more than that. For instance, consider the example of one versus two lights being lit in the steeple of the Old North Church. If that's all you see, it has no representational content; but if you further know that 'one if by land, two if by sea', then one lantern being lit has content, and it represents the English attacking by land.
The trouble is, of course, that the intentionality thus bestowed to the lantern is derived from that of you, who knows that 'one if by land, two if by sea'. Since you already possess intentionality, trying to explain the intentionality of your own mental states---i.e. how they come to refer to anything---in the same terms as we have just explained the intentional, referential nature of the one lantern burning in the Old North Church will run into the homunculus problem.
This is independent of whether mental content is narrow or wide---the important thing is that it represents something; whether that something is, say, the apple out there in the world, or the conditions caused within the brain by the presence of that apple, or even the phenomenal experience of that apple is immaterial.
And it's there that my model comes in (if things work as I think they do): by collapsing the symbol and the entity using it as a symbol---the representation and the homunculus using it; you and the lantern at the Old North Church---into a single entity, I think it's possible to get rid of the regress. So, a von Neumann replicator evolved in conditions caused by the presence of an apple uses itself as a symbol for these conditions, reads the information it has stored and causes the body to perform actions appropriate to the presence of said apple. One might call this an 'autotelic symbol', because it derives its referent not from something external to it, but rather, from its own form (and because I just learned the word 'autotelic').