Trucks get pretty bad mileage with camper aboard. However, in this area, regular gasoline is quite a bit cheaper than diesel. Assuming the same for you, if the gasoline will do the work and it sounds like it would, I think it would be a good choice. I towed a 4000lb boat quite a lot and it was fine with the Chevy equivalent. Brholt doesn't seem to have a problem with his.
'10 Ford F-450, 6.4, 4.30, 4x4, 14,500 GVWR, '06 Host Rainer 950 DS, Torklift Talon tiedowns, Glow Steps, and Fastguns. Bilstein 4600s, Firestone Bags, Toyo M655 Gs, Curt front hitch, Energy Suspension bump stops.
NRA Life Member, CCA Life Member