Keep doing what you are doing. The amount of erosion in that area should be as minimal as water can be since there is no fetch to make waves. I think using anything that would float, like RR ties would be very difficult to secure to the ground/bottom. What does erode naurally should not go far and will only end up basically where you want it anyway for beach cat use. You could probably rent a rubber treaded Bobcat that would get the job done quicker for a reasonable price if you do not want to keep doing it the way you described. I am looking forward to using this area for the Wave regatta in May. Thanks for getting it ready for us!