Is your lighting integrated into your hood? That would be the problem. I have an 'open' top tank like that have cut a bit of polycarbonate to fit on the top, cutting it to fit around the skimmer and filter. I then have clip on lights which hang above the tank. I have no other suggestion for you i'm afraid!
If you're not keeping corals or live rock, you could get a few cheap compact fluorescent bulb clip on lights from ebay. I had a few one on a small freshwater cube that was running a 9w bulb, cost me something like £10
All the best, Dan