Frontal Area

BarabooBob wrote:
Before I bought my truck and TT I did a lot of research into using a topper to help with drag from the trailer. Most of the articles claimed that a topper did nothing to help with trailer drag because the space between the topper and trailer was big enough to eliminate any benefit. they even tested canoes and kayaks to see if there was a benefit. Nothing seemed to matter much.

This is a huge part of this discussion. The turbulence created behind the truck can have almost as much impact as the resistance at the front. I read some studies regarding removing your tailgate to increase mpg. They uniformly did not support this. Today's pickup trucks are designed to travel with the tailgate in place and closed. Similarly there were studies about putting a cab height canopy on a pickup. These studies concluded that "some" toppers can improve mpg ratings but not by a huge amount.

So, I agree with those who say the frontal area, all of it, needs to be considered. Any part that is "hidden" by the TV is likely to experience a lot of turbulent flow coming off the truck.

I tow an Airstream around. A few years back I added a bike rack to the back. I immediately noticed a decrease in my mpg and it didn't matter if I had 2 bikes, 1 bike or even no bikes on the back. The apparatus alone created enough turbulence to make the difference. Amazing but true.