I thought about a gasser and went for a diesel. I have a gas engine F-250 for a work truck and a diesel engine F-250 to haul my TC. The gasser gets 11.4 avg combined city and highway, the diesel 17.2 mpg for the same driving.
150,000 miles is 13,579 gallons of gas at $2.50 a gallon or $32,895
150,000 miles is 8,721 gallons of diesel at $2.50 a gallon or $21,802
I change oil and replace fuel filters at regular intervals and have had zero problems with the diesel truck in five years. Fully loaded, with 3.73 rears it will climb hills and merge in traffic with zero problems. With the fully loaded camper on the back I have been getting 12.5 mpg highway speeds, a little better on back roads driving in the low 60 mph range.
I carry an extra oil filter and oil when I am on extended trips and most places will do an oil change for the basic price with no problems.
In my opinion, the difference between gas and diesel in power and torque is stunning, buying a diesel will not disappoint you. My gas truck would have split a seam well before my diesel truck even got into the power band.