Sway

If you have ACTUAL trailer sway while using an anti sway system it is probably either improperly sized or improperly adjusted. Another possibility however is that it's the trailer itself. Axle alignment is one thing that can create the oscillation necessary to generate trailer sway so spending some time with a tape measure would be a good idea. What I suspect is that you're feeling bow wave effects from passing trucks, not trailer sway. Anti sway systems will certainly go a long way to help reduce bow wave effects but remember, even OTR trucks experience this phenomenon as they pass each other. That MAY be what your wife is referring to when she mentions "normal sway".
Good luck / Skip