You don't neccessarily need a Superduty.
An F150 with the 7700lb package will pull 6000lbs OK.
7700lb package is 5.4L,3.73 gears,trailer towing package,stiffer suspension,245/75/16" tires and I'm not sure what else.
All I know for sure is that my 2001 with the 7700lb package pulls my travel trailer(5000lbs) much better than the 2000 F150 that had the 5.4L,3.55 gears and 17" tires.
There really is no comparison between the two!!!!