Recently loaded a half a pallet of mulch onto the bed of my 2017 F150 4wd 5.0 supercab shortbed, WOW, it sure did sag. could have gone hunting if it had been at night. That being said, would like to beef up the rear shocks...nothing drastic, but increase payload capacity and maybe even allow to the truck to rice and handle better. ANY SUGGESTIONS as to what type or what shck to buy to achieve this ??? Thanks, Bryon in Delaware