Hi James

You wrote:

your premises are consistent with the possibility of perceiving at least some of what is in the head directly,

But perception is an experience - direct or indirect - of what is at the very start of the perceptual process. That is, we can only visually experience - directly or indirectly - those aspects of the world which impinge on our eyes, and the only thing impinging on our eyes is the light from the scene in front of us.

And even if visual perception were a direct experience of something physical inside one's head, that perception would still require a time-consuming processing of information, and so the same logic would still apply.

Derrick