[skyking]

I think you greatly overestimate the heat from your engine. I bellied my Dodge and ran with NO FAN for over a year, only using the electric when towing the 5th wheel in stop and go or in the mountains. On the highway the fans can be left off.
http://ecomodder.com/forum/showthrea...sel-21857.html
I'd do the belly for sure.
Do you tow 5th wheels?
If not, we could design a very very cool adjustable aeroshell/canopy/travel trailer deflector setup. Time consuming and not cheap, but huge returns.
Think of a transformer back end.
When you deadhead, it would drop down to the best aeroshell you could do. When you tow a TT, it would come up square and have a deflector panel at the back 50% to get things started up.
The whole thing lifts up for total access, plus add a big side door or doors for filling that tank and getting to tools. Bonus is dry place and tools.