The “baseplate” is fixed on the deck. The hanger rotates around the turning/pivot axis, as it must when the wheels are in contact with the ground. In the first animation I’m showing the deck statically tilted, with its rake/offset (i.e., axle distance from axis) and height changing. In the next one, I’m also simultaneously tilting the deck to illustrate this point, if it helps more.

I cannot explain in words why offset doesn’t change axle turn, after so much talk in online communities about this or that “turny,” “divy,” “linear,” “surfy,” etc truck has cemented this absurdity in people’s minds. It’s simply so, when there’s only one pivot axis. The axle, which rotates around the pivot axis, turns simply to keep both wheels on the ground. Please take a moment and look at these two animations. They may be very basic CGI, but what they depict is as real and essential as it gets. This is how skateboards turn.

I graphed the lean to turn function (given in the academic literature) for various pivot axis angles. The x-axis is the tilt of the deck (lean) and the y-axis is the turn of the axle relative to the direction of the deck. I graphed it for different pivot axis angles.