So I have a 2' x 2' x 4' enclosure for my cham but the top of the cage that is mesh is only about 12'' wide a I don't know what kind or size of uvb bulb to get? I'm not sure if i should get a t8 or t5 because im planning to place it directly on the cage. Not sure if i should just get the 24'' uvb even though most of it would be on the wood instead of mesh.