extending the hitch out of 2015 Ford Super Duty

RZR's weight ranges from 1000-1500lb's bone stock, depending on which model.
You can also easily move up to 1500 or 1700lb weight bars with the Reese, as long as it's not the older design. That would probably be what I would do before getting into suspension mods. That way if you tow without it you'd have the 1200lbs to use.