Really really confined space

I'd really appreciate any advice on how to make this work.

I've got a tiny space to work in, by tiny I mean it's about 1 1/2' x 2 1/2' x 1" (WxHxD).
I've got the ventillation and air flow mostly figured out. I have 1 fan for it, its just a small desk fan.

I know I'm gonna grow in soil, just don't have the $$ for hydro right now.

I'm planning to use 250 watt flourescent bulbs since the space is so small, I definitely don't want it to catch on fire.

What I need help with is how to keep light from seeping in from the vent hole, I can't find any duct stuff small enough, and I can't make the hole bigger because of the fan and wiring.
I also can't figure out how to attach the light fixture in such a small area with out it causing problems when the plants grow.
I know there are methods to keep the plants short, but I'm still worried about scorching my plants.

thanks

All images off yahoo image search.
Ideas...

you can do it just have the fan blowing across the top of the plant and light. i do that with mine i keep the light 1 to 2 inches away and they love it. search for LST to keep them short and bushy