Chace,
That's pretty creative, selling the wife on the EZ by claiming you will get better towing mileage! Just don't let her break out the calculator and start checking mileage, cause I'll bet your mileage will decrease by around 1 mpg.
I love my EZ, but certianly have not seen the mileage increase reported by some.
I don't do enough sustained towing to pass judgememt on what effect the EZ has on towing mileage, but on a typical tankful, I tow a 10K load maybe 100 miles out of the 450 or so total miles between fillups, and I've lost around 1 mpg since the EZ (definately worth it though). Maybe I'm losing a couple mpg empty and gaining a little towing, who knows? Let us know how you make out towing. I know you will appreciate the extra power regardless of what happens to your mileage.