Wheel alignment on new motor home

The reason a straight axle is used on trucks is not because of the great ride. It is used because as load increases the ride height changes but since there is a single tie rod between the steering knuckles the toe will not change. The steering wheel may move off center due to the change in angle of the drag link, the rod from the steering box to the left steering knuckle, but the toe remains constant. If the camber is changing with load then you are overloading the axle to a point that is dangerous. In certain instances changing the caster will have an effect on straight line stability but this makes the steering heavier at low speeds. Remember all designs specifications are a compromise to accomplish the best result from multiple requirements.
Randy