Nice idea, shame your original post got overlooked, next time it might be an idea to bump it.

As well as sorting out the light leaks, I would make one other change. I would move the intake fan near to the bottom on one of the sides (about the same height as the top of your pots). That way fresh cold air will come in through the bottom intake, pass up through the plants while being warmed by the light and then get sucked out the top by your extract fan.

You could also use black stockings/tights to reduce the light leak through the fans and act as a dust filter. (idea stolen from Bigtopsfinns grow cabinet +rep him if you use it )