A lot of that push from passing trucks is the bow wave of air that they are creating.To break that and lessen its effect you have to make your rig more aerodynamic from the rear.there is a huge low pressure area at the rear and when a truck breaks that it will push you around.
A lack of streamlining causes a partial vacuum to form at the rear at highway speeds. This causes turbulent air in the form of large vertical eddies to tumble into the partial vacuum and the large alternating eddies cause the RV to sway. Disturbances from passing vehicles or obstacles tend to amplify these eddies and increase the vehicle tendency to sway, increasing driver work load and fatigue, increasing drag and lowering fuel economy. Streamlining the RV by tapering would be the best solution but is not practical
Air Tabs are one way to make this happen.
