Desert Captain wrote:
Since I sold my TT and truck 5 years ago I no longer have dog in this fight but:
{Currently have a 24' Class C and usually tow a 10' cargo trailer for my Indian Springfield.}
The OP asked and actually having had first hand, real world experience I shared {see my earlier post complete with a pic of the rig}. Unless you have some, "Frankly Scarlet"...
Set one up correctly at the rear of the truck, experiment until you find the optimum angle of attack and they work. It is just that simple. I never thought 1.5 - 2 mpg was anything to write home about but over the first year it paid for the deflector. After that it was a savings in fuel costs, not a lot, but free.
:S
That is my thinking. I can buy a used one for $120 and the first trip we have planned if I get 1 to 2mpg better it will pay for it. But very little positive vibes for them.