Welcome to the forum. If it is at all possible make it taller. Its like this. 3'-1' for lights etc. = 2' - 1' for the pots the plants are in, a couple inches for the space to the light, you are almost in the hole. Check out some journals posted by others in this forum that have done what you are considering. It sounds like you have a pretty good idea of what is needed, it would be a shame to waste the effort by 'shorting' yourself. VV