FWIW, we had a 1984 Chevy heavy half ton with a 6.2L diesel which had 130hp@3600rpm and 240ft/lbs of torque and it pulled our Nomad Century 30' TT several years around the Midwest and a trip to the smokies - Cades Cove etc and over the mountain to North Carolina and the Outer Banks on the Atlantic.
We've always lived in West Michigan on the lakeshore and often went to and all around the U.P., Wisconsin etc. too. Wasn't fast by any means but always did the job OK. Also pulled our 27' Sea Ray cabin cruiser (26' 8" on a heavy dual axle trailer with 45 gal of fuel onboard - a little over 8500 lbs total) all around the state and in and out of the launching ramps with the 6.2 diesel with no problems. Slow climbing steep hills with the TT or boat but always made it up and over. Sold it with 168,000 miles and never had any problems with it. Less power than the baby Duramax has but was a heavier truck. Of course, back then, RV's had no slide outs in them but did have a much heavier frame.