Mount your light on the ceiling right in the middle of your space. NOTE -- Avoid hanging the light with a chain or any other mounting
technique that drops the light below the ceiling. You are going to want every inch from floor to bulb. You should have about 6 feet on
either side of the light to work with.
Remember you have to fit a fan somewhere too.
Number of plants depends on wether or not you stagger your grow. If you just have that space and one light you have to grow linear,
means veg the whole room at 18/6 or 20/4, switch to 12/12 and flower the room. Means you have to figure on having all the plants
get large at the same time. Inefficient and slow, but that's what you got, eh?
Pretty safe to figure that if the room is only 2 feet deep your plants won't grow more than 2 feet wide either. The math suggests you
could squeeze 6 plants in there but that would be too full as flowering proceeds. Start with 4 and see how that goes. Also be a good idea
to get some of the smaller-sized tomato cages. They are like a wire basket that contains the side growth. They are less than 24 inches wide and will
be a big help, guaranteed.
PM me if you decide to trim your plants to keep them a certain size or shape. I can help you there.
Good luck and keep us posted, BigSteve.