Those plants are really really tall and healthy! Nicely done. They stop stretching when ever they're ready because they're autos unless the light is too far which I don't think it is. They would have loved LST! Try tucking the fans that are blocking the bud sites rather than defoliating. The plant can use all the green it can get to create sugars for bud development.
What are the light/dark hours on the clones? You can run them 20/4 just like the autos.
What are the light/dark hours on the clones? You can run them 20/4 just like the autos.