Just a personal observation-experience... I bought a new 5.7 ltr Tundra a couple years ago, primarily to use as a toy hauling vehicle. Looking back, I wish I had spent the same or less on a used Diesel. The Tundra gets very little use and pretty good mileage when not towing, and only 8.5 to 9 mpg when towing our 24' race trailer. As little every day use as the truck gets, I think I would have been better off with a used 3/4 or 1 ton diesel. My friends get 13 to 15 mpg with theirs. Of course if it is used more on a daily basis as transportation instead of primarily a tow vehicle, it wouldn't really be an issue.
Scott