Skunk #1 Stretch

Hi Peeps, Im doing a grow of 4 skunk #1s from royal queen seeds. I'm growing inside a 1.2x1.2.2m tent in 5 gallon buckets. Just wondering can anyone tell me how much these plants stretch when flowering. Taking into consideration the height of the buckets and leaving about 2 feet under the 600w hps I have about 1m to 1.1 meter growing height without any trouble. any advice on this would be great

Skunk used to double its size in streching stage

So 50cm should be pretty save then that's roughly what I thought. thanks