I have a 34' Fleetwood Southwind Storm. At 17k pounds it is a relative lightweight. I've had several dangerous events involving wind and passing tractor-trailers. My air-bags made it worse, I'm sure.
I designed and had a local welder make rear track-bar brackets for my F-53 chassis. Tractor Supply carries the adjustable center links. Made a world of difference.
If you are a DIY'er and interested, mine is similar to these: Oemy's Web Site - DIY Trac Bar
We then took a 3k mile trip to Durango, Co with strong, constant southerly winds on the way out on I-40 and northerly ones coming back on I-70. I'm glad that thing was back there. It stopped at least 90% of the tail-wagging. The pressure wave from passing trucks (usually doing 90+ mph) now has little effect. Prior to install I'd have to counter-steer into them by turning the steering wheel to the 2 or 10 o'clock position and then ease off...just...enough.... I must have done it right, I still have my side mirrors.