[crmears]

My situation is not one typically discussed here but the phyics of fuel economy are the same. My 2008 Class A diesel motorhome gets 8 mpg at 65 mph. I have a goal of getting a solid 11 mpg. It is 26,000 lbs, 8 by 13 feet for a frontal area of 104 sq. ft. It is shaped like a brick (front and rear) with rounded corners. It has 2 large ac units on top and a couple of vents stickins up also. The engine is a Cummins 360 hp, 8.3 liters, variable blade twin turbo, computer controled fuel injection and computer controled transmission.
My assumption is 70% of energy is used to overcome aerodynamic drag so that should be my focus. I own a body shop have the means to create a front end that looks like a Japanese bullet train with a remote controlled liftable air dam 3 inches from the pavement. I could also modify the rear to look like the rear of the bullet train.
Would this be enough to gain the desired 3 mpg? Or could it even give me more gain? Any other ideas.
Thanks,
Randy