Lumber Rack Accessories - Kayak Transpor

Anyone know of a company that makes Kayak accessories for lumber racks? I have a lumber rack on my pickup and looking for either J Style holders or Kayak pads to attach to the (~2 diameter) round cross bars. Looking to carry two kayaks on their sides on the rack.

Castle craft

Thanks ! Anyone making J Style hull rais
ers that fit the lumber rack the same way?