Good to see the work in progress.
I know your running this as a trial and error sort of thing but I would recommend you bump up your light levels if possible, you said your using only 50watts flourescent? I would stick at least 4 more 23 watt CFL's in there especially as your plants get older. That will triple your current lighting, and not be too expensive, You can always use the CFL's around the home after you upgrade from them. use one lamp with a 100watt rating, you can screw in a double socket Y shaped thing that allows you to screw in 2 bulbs, You can screw two more of the Y's into that double socket and have 4 sockets, Your bulbs might cost something like 30$ and the Y's are like 3 or 4 $'s.
did you narrow down the cause of the drooping?
I hope you get it all sorted soon enough, and the funds allow you to do so, My funds are pretty backed up right now... I know I'm gunna need a carbon filter eventually but I just cant afford it! lol ahh well I got some incense I can burn