I've got a challenge for the more creative people on this site...
We bought a travel trailer last year and learned quite a bit in the process of shopping for one. Like the cars on a train they are boxes on wheels to maximize interior space and utility - round the corners and it screws up something or other on the inside and pushes cabinet costs skyward. And at $15,000 on up, people won't pay for much in the way of fancy aerodynamics.
Also, it's a fairly major industry in some US states. (It's actually rather surprising that anything is still made in the US and not imported from overseas.) I imagine it's dying a horrible death right now - along with a lot of real jobs where they create real things.
Anyway, I thought I'd challenge the people on this site to come up with suggestions on what the trailer designers could do, cheaply, to improve the aerodynamics of their products and save their industry.
Just Google "images" for travel trailers and you'll see few design concessions are made by the manufacturers towards aerodynamics. (The 5th wheels are little better.)
eg - this is like the one we bought... a K-Z SPREE and I sure hope that big indentation in the front centre is a fancy aerodynamic trick - to me it sure looks like a parachute.
http://forum.ecomodder.com/images/smilies/eek.gif
http://i1.imagesrv.com/1/564/i/50118...83_1037856.jpg