Just add another 10 feet when you need it, using a bowline knot or spliced eye. Add a snap shackle or strong hook to the end if needed.

I use a Forespar Motor Mate for the motor, and use the spinnaker halyard for the dinghy. No need to buy a dinghy lifting harness, make one yourself out of spare rope remnants. When lifting the dinghy I use the spinnaker halyard -- my wife handles the winch and I guide the dinghy. When single-handing I can launch and retrieve the dinghy myself by lifting it vertical from only the bow -- I lift it almost all the way then lock the halyard while I maneuver the aft end. It might take a few trips back and forth to complete all the maneuvers, but it gets done without any real stress.

Harbor-hopping in fair weather I just remove the drain plug and carry it on the net, but if heavier weather is expected I invert the dinghy and carry it upside-down, well tied.