Nice truck.
I have 3.55 gears and kinda wish I had 3.73 when I'm towing much more than a couple thousand lbs. My current 2.7 F150 only has like 12XX payload, so I DO NOT tow heavy, my previous F150 with a 5.0 and 3.55 was what I would tow 6k with. Payload was right at 1700
My advice - look at some of the towing forums or other truck forums before you decide on that 3.42 ratio.
Especially if you head up into the hills. I see you are in Greenville, so I have to think you'll be heading up into the Blue Ridge! 3.42 will do it, 3.73 will make it a better experience on grades.