My 2007 Harley Davidson F150 AWD will be towing a 26' travel trailer weighing 4500 lbs dry starting this summer for camping. I have the 2" block removed from the rear leafs to level the truck. I like the look and ride a lot better with it lowered slightly so I don't want to put the blocks back in as I use the truck as a daily driver as well. I think I'll be looking at 700 lbs of tongue weight and stuff in the box. Everything else will be loaded in the trailer.

I'm worried about sag when towing and stability. Would a set of Timbrens or maybe a Hellwig helper spring work for my situation? And not affect me when I'm driving unloaded? Or should I just keep it stock? I will be using a weight distributing hitch. I have spring codes UUMM on my truck and 305/40/22 Cooper Zeon LTZ tires rated at 2601 lbs at 50 psi.