Yes, though in that tank I would do it anyway since it is not a reef and the lighting is not really important.
Actually, at this point the egg-crate has been removed and the screen is attached to the rim of the tank and the side of the light directly with velcro. It just looks a bit neater as well as helping to prevent any possibility of forgetting to put the cover back.
Many people who have to put something under thier lights use several layers of bird netting in a window screen. It is lighter and allows more light through.