Passing trucks have a wind dam that is causing the problem.
Gas MHs have a pivot point that balances the load, as a result when you look at an RV think of a teater toter child's toy. The further back the axles the less the wind dam will effect you.
Pull trailers have an exaggerated issue due to the distance the hitch is behind the tow vehicle's axle. The fifth has less reaction due to the fact the steer axle is unaffected by movement of the box.
My money is on the fifth, however, none of the RVs are unaffected by the dam(I have owned all but DPs).
It should be noted that planning can mitigate much of this problem. I'm not talking about trip planning, but rather weather planning. Tail winds for you mean a larger stronger wind dam for the oncoming truck, and less dam for a Passing truck. Although some of us stay off the road in windy conditions, others really have no other choice. However understanding what will happen due to wind you can prepare for the inevitable, by slowing down so you can react properly. Pull to the outside of your lane as the truck closes in so you are in the weaker stream. And keep aware that trucks or other RVs are approaching.