6.6 gasser MPG

Looking to get out of the 3.0 and into a 6.6 gasser. I don’t hate my 3.0, but have 67k on it and am kinda over the diesel thing. Life was so much simpler with a gas truck. I can buy a used ‘24 2500HD AT4 for roughly the same money as a spanking new 3.0. I do enjoy the fuel economy but I don’t enjoy all of the things that come with newer diesel trucks. I do drive a lot for work and get paid the going rate per mile. Oh almost forgot, I messed up and bought the Carbon Pro and wasn’t aware that you are very limited on covers and no solution for a camper shell. Appreciate the feedback.