2018 F150 HDPP 3.5 EB 6.5' bed update. Did my first long tow this week - 920 miles. The only significant change I made to the truck prior was a new set of Pro Comp rear shocks. I scaled it as we left the house loaded for the trip:
FA 3300 Lbs
RA 4500
GV 7800
Trailer 7700
GCW 15500
That's 4 people, full 36 gal tank of gas, and 3 dogs in the bed. Trailer was lightly loaded w/o the usual 400 lbs of dirt bikes in the back. Every value is within spec.
Towed I5 South from Portland OR to Bakersfield CA. 920 miles, averaged 56 MPH and 9 MPG. Truck handled beautifully. Very stable, smooth, quiet, and comfortable. Absolutely zero issues or complaints. I'll be heading back North in a few days. It's a long drive but not stressed about it as I know the truck (and family) will be fine.
Mike