There are some options still to slow the stretching a bit and I would reccomend that you strip off the lowest vegetation as well. No leaves etc at least for the lowest 4 inches or so. I stripped the lowest 12 inches on my 4-5 foot plants and that was a gradual thing. Take some everytime you tend to them.
The benefit is you direct more energy to where the high grade is produced but even more importantly you allow for better airflow in under the canopy.
The absolutelly most important building block (given you have sufficient light) for a plant is carbon and ALL of it comes from the air.
Look at your grow room and try to figure out how the air moves from intake to exhaust. You want air to come in, move to the centre of the plants still on floor level and then get sucked up through the canopy.
Try to make that path as easy as possible for the air and you will get more and better weed for it.

Looking awesomne by the way.

To stop the stretch a bit you can break the main stem of the plants a bit under the forming colas. Sounds drastic and I guess it is but I did it to a few of mine as last solution and they got stunned for a few days then continiued like nothing had happened but at an angle, a week later I broke them again and made them grow like the letter "Z" almost. Feels like a terrible thing to do and a hanging top cola is no fun to watch but a few days later it just mends and starts aiming for the light again but at an angle.
Might be something to consider if it starts to become a serious problem. Also in a tight space like yours an even canopy is an absolute must so it might come to that even for canopy reasons if you have some that grow faster or slower than the others.
It's just this time anyway, in the future I guess you as me will use clones.

Puffzter
Puffzter Reviewed by Puffzter on . White Widow cabinet grow Well, I figure it's time I start a log. I bought Feminised White Widow seeds and put 4 seeds into "Root Riot" organic starter cubes. When the first baby popped up I proudly started this thread. Out of those 4 seeds I got 5 babies. (Photos in the linked thread) I had to separate them and they seem to be fine but the 5th one is a bit of a runt. We'll see what happens. This is the cabinet: Rating: 5