PVC will crack and break, especially in current or when temps get colder. Been there, done that. I use a 4 foot piece of bungee cord with a stainless steel ring on one end and tie it off to the cleat on the other end. My anchor is just a solid fibergalss rod from grainger with a stainless tip...
If you have carpeted bunks, before you load your boat back on the trailer on a warm day, take a block of "gulf canning wax" and rub it all over the carpeted bunks, it will slick them up and you will be able to slide the boat off with ease. Just reapply every so often when the wax has worn off...