I own an 07 3.0 and pull up to 3500lbs on flat to rolling hills. Low profile trailer.
When on the highway in rolling hills I use the sport drive to keep from constant shifting on grades. (6th gear is more of an overdride anyway)

If you are going to drive in mountains or long distance high speed trips you might
want to consider the 4.8 especially if you do a lot of towing in these conditions.