This is probably what you had in mind. I would expect it to work well on the rear of a van as the shape is similar to my truck with the shell. I get 1.5 to 2 additional mpg using this deflector. Two things are critical, first you need to get the angle right. The wing should be aimed right at the top leading edge of the trailer. You will know when you get it right as there will be no bugs on the front of the trailer. Second it needs to be as far back/close to the trailer as possible for maximum efficiency.
At $3.50 a gallon it took about 6,000 miles of towing to pay for itself which took a little over one year and I am delighted with the results as we have averaged 12.5 including a lot of serious mountain driving. Mine was $377 delivered from Icon Direct. :C
