At the Aerodynamics Forum you could check out BamZipPow's 'Boat tail project based on a single wheel trailer.'
http://ecomodder.com/forum/showthrea...ler-26997.html
The idea is to create the elongation necessary for a significant drag reduction by use of a gap-filled trailer.
*The trailer gives the length
*And it can carry some load as well.
Here is the concept
So far,BamZipPow has shown up to a 2 MPG improvement by pulling the trailer.
His T-100 truck is also probably the world's fastest for a standard powertrain,which reinforces the validity of his drag reduction.
*For more insight,please see the thread 'full-boat-tail gap-filled trailer for T-100' at the Aero Forum.
http://ecomodder.com/forum/showthrea...ta-t-7839.html