Do not fear the reliability of the gasoline engines, they are quite reliable. The gas versions of duallys are out there. I found one ford in Missouri and one a Ram in NC by doing a quick search using carguros. I have a Ram 3500 SRW hauling 5000 lb 8’11” that’s 8’ wide with no issues. Yes in the mountains it takes a little more throttle to get up and over and I manually gear down on steep down grades, but I like my gasser. Also the gas versions give you more payload capacity as well. I done the math and there is no way to make a diesel pay for itself, but if you plan on pulling 20000 lbs a diesel is better option.