Basically I have learned to suck it up at the pump...
gasbuddy.com helps.. after a few trips in our new 27k we get around 8 mpg, but the overall cost of the trip is less then hotels plus meals so traveling in first class on the road the 8 mpg is not the real issue...until you pull in to re fuel
You can save a slight bit by not running a/c, going up hills at 50 mph, etc, but really in the end these things suck gas, though as posted earlier, not as bad as boats...BTDT,, I found owning stock in an oil company helps offset the pain at the pump... do get gas rewards credit cards..or some card that rewards you for the purchases.
Enjoy the view as you drive!