I do it a LOT. I have a length of rope that is about twice as long as the boat/trailer. When I get ready to launch, I lay the rope on the deck to make sure it is not tangled and hook one end to the trailer winch. The other end is always attached to the bow eye. After I unhook the winch from the boat, remove the tie-downs, and the motor toter, I just back in the water slowly until the boat floats and then pull forward enough for me to get out of the vehicle and unhook the rope from the trailer. I then pull the boat over to the dock, shore, tie up and go park the vehicle/trailer.
Loading back up, I back the trailer in the water until the support bunks are just under the surface and then drive the boat onto the trailer, hook up the winch strap, get into the vehicle and pull away from the ramp a good ways to prepare to leave.