I just finished a short trip with my 2003 5.4, towing a 5,200 lb. 25' travel trailer into and through the Smoky Mountains in Tennessee and North Carolina. While my truck handled it just fine, I would hate to try it with anything much less in the way of power. While at the campsite, I talked to a man with a 2005 4.6, and he was definitely unhappy with its performance in the hills towing a 4200 lb. trailer. BTW, we both have the 3.73 rear end.

 

Picked up my 2012 XLT Screw EcoBoost w/ HD Payload and Max Towing a few days ago. My trailer weighs in at 6000 lbs GVWR so I am thinking this is going to be a great combination. Planning a trip from Texas to Maine soon so I will know for sure once we get there.

 

I would imagine that trailer will be a walk in the park for that truck.