light and ventilation setup, is it safe?

Im doing a cabinet grow this time around, and that means I need to get a smaller light and worry about ventilation.

My cabinet has a shelf on top that I was thinking of hooking to chains (it has screws underneath but id rather be safe) so its adjustable. What I was thinking about doing, instead of buying or building a nice air cooled reflector for a 250/400w hps, is cutting a hole in the board for the light to shine through, put a peice of lexan glass over the hole (keep heat out) and then just run a lot of ventilation out the top of the cabinet to keep that upper area cool.

I think this could work well with what I have in mind, however, being a peice of cheap cabinet would, I fear it may catch on fire from the lights heat. is there something I could place on the wood to prevent this, or maybe I could just get a peice of lexan cut it the size of the top shelf and just hang that up and set the light on it?

any thoughts appreciated

I have some ideas, but do you have a picture of the cabinet ? or the brand?
What material is it made out of even?

Without knowing the only thing I could think of is fire walling it if it's wood. That would at least resist/retard the fire assuming there was one.

But it's hard to say if it'd be too hot, depends on what type of material (paper/metal/wood/plastic) it is.

it is a closetmaid cabinet from home depot, its made out of cheap wood with white laminate. I could get a picture of it later tonight if needed.

mount the light on the bottom of the wood.

I have somethign similer to what you have. I got a 6 foot tall wood cabnit from home depot. I put the 400W hps at the top with a reflector. No cool tube nothing. I have 2 fans moving hot air out. One is to the left of the light and is a 6in fan. It pulls alot of air. The other is on the cieling and is just one of those little crappy fans. Anyway i cool the unit with A Ac wall unit (99$ walmart) i put it in the side in the middle. It works for me ive gotten some good dank out of it.