When I first retired and we purchase a TT I fretted during trips about gas mileage. For some reason I had set a goal of getting an average 12 mpg...not to be. We have a 27 ft Lance trailer and tow with a 2009 Ram 1500 hemi. I get between 7 and 13 mpg so I figure 10 when estimating.
Everyone always asks what gas mileage I get with the rig. My answer now is it's always between F and E. When it gets down toward E I add more gas then I get F.
I quit fretting about mileage about two years ago. As others have said we RV because we like the freedom to go where we please when we please and that is.......PRICELESS!