Exactly.. youve got 4ft of height total.. Lets say the pots are 10 inches tall.. The vipar 300 is about 3 inches thick.. So if hung at the top, with zero space inbetween.. from light to the pot would now be 36 inches total height left. If you keep the light 18 inches from the canopy at all times, that means the max plant height would be 18inches.. Lst would be the best option.. But autos can grow just as wide as they can tall. I started out with a 2x2x4 tent and an led. I out grew the tent many times, both height and width, with just one plant.So an option might be just leave it at the highest point possible for the entire duration and just LST and not adjust the height ?