Sounds exactly like what I have been doing for decades at Ningaloo. We leave the boat in the water there most of the time for the 2 -6 weeks of our stay as it is a difficult beach unless the tide is very low and there is no water coming over the outside reef. We have probably beefed it up a bit as is it has to be there day and night but principle is the same. We use 12 mm polypropylene, renewed every two years, running through a 50mm Stainless davit pulley with a 10mm pin attached to the end of a substantial chain and 15 kg of anchor ( This is for 5.8 to 6 metre boats--I said it was substantial.) Up near one end of the rope I have spliced a long loop in. This has your mooring rope attached. Run the other end of the rope through the pulley and tie the two ends together. You now have an endless loop, restricted only in movement by either the joining knot or spliced in loop hitting the pulley. Hook your boat up to the mooring rope and you can then pull it in and out as you please. When you have it where you want it , we tie the beach end off to a long gal star picket driven well in . This beach gets very surgey at high tide, and is subject to a lot of wind, and this has served us well.
I'll' try to draw a picture.