Aeromodding is definately the way to go to get substantial fuel efficiency improvements, since it sounds like you have to tow and need to run moderately hard to do it under those conditions. Consider the trailer as equally a target for aeromodding, as well as the gap between pickup and whatever you tow.
I'm similar - everyone keeps trying to sell me on smaller vehicles, but what i'm asking questions about will actually need to tow stuff which I can't do with a smaller vehicle, so i'm going to have to aero the crap out of it.
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PS - I thanked slowmover for that post, because although i've read the similar multiple times before, that was the nicest most coherent summary i've heard - having a transportation strategy is almost more important, the sole figure being total cost per mile, possibly changing driving habits and similar in some situations, whether to have 2 vehicles or when does 4 make sense, etc.