The original Ford design was the flat plate with weld-nuts. Design was good because that hard to reach forward bolt would then be easy. The other advantage of the flat plate is it distributes the load over a larger area with prevents the thin bedside metal from deforming. Nutserts (riv-nuts) deform the bedside the worst. The metal is really thin both on the bedside and the top. Of course big washers both on top and bottom will distribute the load sufficiently. My rig has a combination of the weld-nut on metal strap and the big washers. Big washers are convenient in some places, but the handiest is the metal plate with weld-nuts.