From my limited reading on the topic, I'm with PaulC. If your trailer doesn't extend taller or wider than your tow vehicle, aerodynamics isn't a notable factor.
Hmmm, if aerodynamics was playing a major role, wouldn't sloping the front of the trailer back cause lift and handling issues
I didn't have a wind tunnel, although I'm shortly getting a fancy mileage / trip computer to do some mileage verses weight / wind resistance testing. If you were closer we could use it to run some tests.