I dont know if this is exactly how you are thinking of doing it, but this is what I would do. First off, make sure you either have the measurments or the actual light you will be using. Do as you planned as far as leaving room in the rear for the filter. For example, say your tank is 20 inches deep and your filter will need 4 inches. So, cut the glass so it is 16 inches wide. This will leave room for the filter. Then, measure out how much room of that 16 inches needs to be dedicated to your lighting. Lets use 6 inches.
Cut that 16 inch piece of glass again, into a 10 inch and 6 inch wide section. Home Depot should sell some T shaped piece of weather stripping (or similar) You will put the "leg" of the stripping between the 2 pieces of glass, and the cross section across the two tops. So, the part that looks more like this " I " will be a buffer between the glass, and the top of the stripping or the " __ " part will have to be glued to the top of the glass. This will create your hinge.
Lastly, you just need some kind of handle, which can be made from anything handle shaped with a adhesive backing, or that you can glue. The striplight I bought for my tank came with two things to raise it off the tank a little bit. They are L shaped and have an adhesive bottom. Attatching this to the glass would make a perfect handle I think.
