Never seen one either. You could always fab something up, maybe recess the winch in a hidden winch plate behnid the factory bumper cover. Anything is really possible given enough time and resources (money). Like the previous reply though, all I have seen are removable winches mounted in the rear receiver.
OME HD; JKS Adj TB; Skyjacker Nitro Shocks; Rancho SS; LT 245 75 16 KM2 on Cragar 16*8; KN Cool Air; TB Spacer; Yakima Rack; Coming Soon.....OBA; Winch; Armor; etc.....