Spray the carpeted bed (bunks) of our boat trailer with furniture polish, after we launch our boat. After the polish is dry, it creates somewhat of a slick surface for the boat to slide up on while retrieving out of the water. "Roller" type boat trailer beds only need to be oiled or greased on each end.
As well as boat polish sometimes, my wife will also apply Vaseline to polish our boat, but without the boat polish. Vaseline can really make the boat coating shine.