you can always multiply TQ to get more but whatever HP you have you are stuck with, so what if it shifts sometimes?

Another thing that helps the newer trucks handle bigger trailes is the vehicle weight and footprint, they are wider, longer and heavier, all help with the overall ability to manhandle the trailer behind it. I noticed also that my 2011 1500 was much more stable towing trailers with 20" wheels than the 17"s, less sidewall flex means better control of everything.