A superchips tuner may help with towing. There is a 'Tow Tune' program that can be loaded, as well as other tunes that come along with it. Our 4.7's use the Superchips 3865 programmer, or Cortex 3950 (same as the SC 3865 with a warranty). I have the SC 3865 and it really wakes up the engine.
(It's cheaper on other sites, such as Amazon.)
Another option is a gear change, either 3.92, 4.10, or 4.56, but this will negatively affect you MPG's.