I drive a diesel. I don't live at high altitude and I only tow a 5,500lb TT. I have a diesel because I want one. Kind of like wanting the GT Mustang (V8) over the base model Mustang (V6), or a big camper vs a small camper. Since when do you have to purchase something based on NEED, or it being able to pay for itself?
OP, you will miss the power of the diesel, but there are gas engines that will definitely get the job done. My cousin has a GMC 6.0L and it pulls fine. Just have to get used to the engine revving all of the time.