I have a canopy. It's a little wider than the bed, stands about 2' above the cab, all corners are rounded about 8" radius. Any idea how much drag as opposed to no canopy? Will I have much more drag with the 22' trailer behind?

The more air flows around the object, the better the MPG's. Here is an article that I wrote about aerodynamics. http://www.dieseltrucksite.com/showthread.php?t=286&highlight=aerodynamics

The difference is minuet when it comes to the aerodynamics of a refrigerator.

More on Drag Coefficiency... http://en.wikipedia.org/wiki/Drag_coefficient http://en.wikipedia.org/wiki/Automobile_drag_coefficient http://ecomodder.com/wiki/index.php/Vehicle_Coefficient_of_Drag_List As from what I found on Drag numbers for Dodge Ram truck range from 0.41 to 0.52.