Nothing is going to stop the big rigs from pushing you sideways. That's basically a severe crosswind, caused by the tremendous "bow wave" of air that pushes into your slab-sided coach. A 12,000-14,000 lb vehicle simply gets pushed out of the way. Even 20,000-22,000 lb coaches get moved.
Anti-sway (aka anti-roll) bars help reduce body roll, but that isn't much of a factor in crosswind handling. Some people like a steering stabilizer to help keep the steering wheel center, but IMO that's more of a feel-good thing than a real benefit.
The rear track bar I mentioned previously will help keep the rear leaf springs from shifting under the strong side loads of the crosswind, so may be of some benefit when semis pass.
See my forum Library article on some common handling problems and the devices available to assist: http://www.rvforum.net/miscfiles/MH_Steering_Handling_%20Primer.pdf