I like the gasser but for the mileage.
There are things you can do. Upgrade the cold air. Increase the exhaust to 3" dual eliminate the cats. These alone will get you to 17mpg
Bigger problem at the moment is at 65 dragging this camper it spends more time in fourth gear than it does in fifth gear let alone six. I can keep it in 5th gear if I draft a tractor trailer. Getting about 7mph