Double the spring line back to the bow. AFTER you have backed off the dock, go forward and release one end of the spring line and pull it aboard. You have distance equal to half the spring line length to work off the dock.
Use as long a line as you have. Be sure to put a pair of fenders forward so you can agressively lay the bow against the dock, use starboard rudder and kick it with some RPMs - the rudder will kick the stern out as much as the spring line.
Piece of cake.