Yes, it should fit just fine on a F350 with a gas engine, and be well under GVWR.
Carbon sounds nice, but it my testing it sure seemed worse at taking impact than an equivalent thickness of fiberglass layup. It's main strength is much higher stiffness, which isn't something that matters on a rig like this unless you make the walls thin. 2" of foam sandwich with FG layup on each side would be plenty stiff. It looks like they are using a mold though, so maybe they are building it more like a Bigfoot or Northern Lite, with outer structural shell, and the insulation and inner wall added later... that's actually what it looks like. Carbon makes more sense then.