So you want to throw away gas mileage?
When a truck drives it disturbs air all the way to the ground. You are now punching a bigger hole in the wind. Adding more aggressive tires adds rolling resistance, more gas mileage gone.
Taller tires throw off the factory calibration and more mileage gone.
If you can find a use for the lift, snow, trails, or even just your ego, then fine lift it. but most day to day actions will get worse.
When you level a truck, then actually put a load in it, it looks