I have not grown critical skunk but i have grown several varieties with similar genetics (skunk/afghan). From my experience the skunk dominants tend to triple in height during stretch. If you have the luxury, I would clone each plant and bloom the seed plant and see what they do, odds are you will find a plant that is critical mass dominant and stay compact enough to grow naturally in your space. If you can't take the time, topping can help control height, but expect them to get bushy and take up a little extra horizontal space. Another option is LST or maybe a scrog, a little more involved and a longer veg time but you can accomplish quite a bit in a small space. Hope this helps some more than none.