Seems to me a carefully engineered steel bed would more likely have a higher payload and the Santa Cruz is 660 lbs.So, I've been thinking about the idea that the bed will be steel and part of the structure. The Ridgeline and Santa Cruz, which are the only other unibody trucks in the US market both use composite beds. The Maverick will definitely have a plastic or composite bed rail of some kind based on those spy photos of the body structure. I just can't help thinking that Ford will do something with the bed other than steel.
Of course, I also predicted that the gull wing tailgate would be a "thing." I could be wrong about the composite bed too.