I've had a few snaking episodes towing with a VW Tiguan AWD, only one started to get out of hand, definitely power off and stay straight has worked for me. Since I've been towing with my V70 D5 I've barely had so much as a wobble, but one thing I definitely wouldn't do is accelerate to try and cure it, I really can't see that ending well. Anyone sandwiched between two HGV's on a four laner is going to be susceptible to it, fortunately that's a pretty rare occurrence in my experience.