Plants usually stretch the most during the first 2 weeks of flower. Depending on strain can triple in size. I don't think you need another trellis out door plants are usually alot more hearty than indoor plants. I grow without any support. Mainly cus I'm lazy.
But coco does have a tendency to produce flimsier plants IMO. You don't see a lot of people using it in outdoor grows.
The point of a top trellis in most grow is to weave limbs so that all buds sites stay relatively the same height, as close to the light source as possible.
In an outdoor grow the light source is usually hitting all areas of the plant throughout the day. Not just the top like a typical indoor grow. Typically you would see people use the trellis on the sides of the plant more like a tomato cage. Just my opinion. There's no right or wrong. And like i said I don't use any.
I have seen people who lollipop outdoor grows it's just not for me. I'd rather mother nature trim my plants for me.