Well think about it inches. You have 48" of space to grow. Depending on your light set up and pot size which can easily take up 20" together. Leaving you with 28" of grow space. You will have to start flowering when they are 6-8" and keep the lights extremely close so no bad node stretching occurs. I would use cfl's for this set up as they dont draw mad amounts of heat and can be placed a inch or closer to the bud spots.
This my first official grow and only cfl only grow I ever tried befor I upgraded HPS. Like you I had limited amount of space. I only had a closet to grow in at the time so I did what I could.
I had the lights very close and flowered at 8 inches. I trained 2 and let the other just grow as you can tell the tall one out of the group..... which kept me adjusting the lights daily. I think I had a total of 26-30 clf lights in there lol got some phat ass nugs though it took a shyt load of lights lol
This turned out to be a very tasty and dense buds with plenty of sugar : ) all from corner house in the hood bad weed. I just happen to save seeds form the best batches and labeled them how potent it was. 3 out of the 20 made it. Half were males and half of that looked good were hermies... can only imagine how hard it was to find balls when you have dense ass plants in a tight spot.....
You can do it though is what I try to display here.