Where is the lateral position of the aerodynamic center? There is plenty of literature that describes how to find the aerodynamic centers (AC) longitudinal position.

But where would it be lateral?

My guess is somewhere near 1/3 out the wing from the fuselage, but I do not know..or would it maybe be close to the mean aerodynamic chord line?
For a simple tapered half wing the aerodynamic centre spanwise location is at:
$$
y_{ac} = {{b}\over{6}} \cdot {c_r + 2c_t\over c_r+c_t}
$$

where $b$ is the span, $c_r$ is the root chord and $c_t$ is the tip chord.

For a symmetric aircraft it should be at the centreline, since it's the combination of the two identical (but opposite sign) locations.

Source is a aicraft sizing code I wrote some years ago, I remember solving the integral for a simple tapered wing.
Looking quickly at design books I can find the following image in Raymer, hope this helps: