I really do not like the idea of asking the power steering to do more than it was designed to do. Specifically, to continually have to overcome stiff springs or hydraulics added aftermarket. Particularly if the vehicle has no power steering oil cooler. Only rationale I can come with to defend the extra resistance is that RV service is usually long periods of straight ahead driving punctuated with parking at the end of the day. Delivery service would be the opposite, maneuvering all the time.