Louvered tailgates normally benefit the hitching/unhitching scenario, but fail to offer any measurable increase in fuel mileage.
As far as mudflaps, as previously indicated, on any road surface with loose material, the rear tires will have a tendency to throw the material onto the lower front portion of the trailer. I have towed in some circumstances where the county had recently placed crushed limestone on the asphalt surface to create an additional wear surface and basically removed all paint from the front frame crossmember after only a few miles, therefore some sort of protection would be warranted if you expect to find yourself on any type of roadway with loose materials.