To me something is not being calculated into the loading is the fact that the rudder has a balancer, which would reduce the servo load . At a certain point( I think its about 25%) the area ahead of the hinge line would actually start to force the rudder away from neutral. One can tell by moving air over the rudder without any linkages attached to it.
When 3D was evolving MAN had a pic of Mike McConville's modified MW 300 with a huge counterbalance which I copied building mine. I had the tail wiggle on windy days and an engineer friend told me what I stated above.
Still, rudders like tons of power even with a balancer.