Wiggle behind car carrier

You can still take advantage of a semi's wake while still maintaining a safe distance. That buffet zone is the trigger point, when you feel it, back out just until it no longer affects you, now you are in smoother air that comes over the turbulence. While you are no longer pulled by the trucks draft, you can still use the smoother top air over the turbulence. The turbulence creates a bubble, like in the bed of a pickup, and smooth air flows over the top of it, and when you just touch the last roller in the bubble, the air flows right over the vehicle. It's not as efficient as being directly in the trucks wake, but you get the same effect, just at a lower efficiency. Takes practice to get it right, but it does help. I can usually gain 1 MPG towing my TT by doing it and still maintain legal distance. The downside, it requires a lot of concentration to maintain that position, and as soon as someone cuts in front of you, its all lost.