This is a really cool thread. Welcome to the forum.
One thing I'd have to wonder is what proportion of your resistance is rolling vs. aero. I assume rolling is much, much higher compared to a car. (Which presumably is why they are switching to the singles for more efficiency.) So what about tire pressure - does everyone automatically run at some "maximum" there?
Do you have any say in how tight your cab/trailer gap is? I have read that the smaller the gap, the better.
I sometimes see trucks from the same company traveling
really close together on the freeway (less than a truck length apart). Presumably they're doing this to save fuel. In that case, the two drivers would have to agree to split the prize.