As MFL pointed out, my buddy knew his Dakota was not the ideal tow vehicle, but it was what he had and it was a limited tow. He really really liked the bigger TV. :)
Also as I mentioned, almost every modern TT is within a few inches of every other, they all have about the same roof bumps like vents and AC and they all have flat backs. Airstreams and some of the shell type TT's are better but I doubt that frontal area is the reason people buy them.
TrailManor and the old HiLo had the right approach but the majority of the buyers simply do not care enough about it to be a concern to the market.