We cannot limit the real to some positive-negative sensory axis (sound-silence, visible-darkness, resistant- non-resistant) nor to some set of co-ordinates on these axes through time. Even after we chart everything that can be charted in this way we’re still left with the axis of real-fiction and perhaps theorizable- mysterious (in Chomsky’s sense).
The attempt to set some limits to knowledge might be tractable of we limit ourselves to what we are proportionate to knowing or most adapted to knowing, or to objects about which we can know not just that they are but also what they are and/or how they work. But the attempt to set limits on things we can know in any way is probably pointless and looks to even involve contradiction, i.e. it’s the attempt to both identify something as mysterious and be oblivious to it.
But limiting knowledge to what and/ or how knowledge is something even STA does, and so Naturalism has to be far more ambitious than that. But it’s just this ambition that divides it from being reasonable.