Diesels often run hot not because of the radiator as much as the oil cooler. When under load the lube oil cooler has to extract the heat put into the oil by the inter cooler and the turbo. The guy that said too much load, toad! Not likely if you have a modern diesel Cat or Comealong. Both will pull a house down, and not breath hard. I used to own trucks back in the sixty's and the average motor was 250 JP. We could haul gross weights up to 150,000 pounds of steel and climb hills ect. So I don't see you haveing a problem with a toad. No doubt you are running a 300 hp or better.
Winnebago Journey 2002 CT34, Cummins ISB 275 HP, Allison 2000 5 speed, TOAD; Xterra 2012 4X4 Auto, driveshaft disconnect.