Great! You got the right type of engine, now you just need the right brand of truck.
Ford makes the perfect rig for the Host Mammoth. The 2015/16 F450 has a long list of advantages over the Ram 3500. Stronger Axle, better gearing, tighter turning radius, G rated tires, more power, quieter ride, lower bed height for easier camper loading, better tow mirrors, stronger factory hitch, bigger brakes, front suspension components from a medium duty truck....you get the idea.
You get the benefits of a medium duty truck without the penalty of a derated engine.
It's all about buying the best tool for the job.