All great answers! Bluemms answer about a Scrog I completely agree with. When I first started growing I had very limited height so I learned to Scrog. I can veg a plant for 6 weeks and get a really respectable harvest in under 40", and that includes the height of a 5 gallon pot and the distance I need from my light. Scrog is definitely something that might help you because you could go with a smaller pot and a less intense light that I have and get a pretty short setup. I posted a picture of a Scrog I did so you can get an idea of what we are talking about.