NIGHT PROJECTOR. If you have a place that you could shine a slide projector onto at night outside you may be able to try this. You will first have to check out local rules to see if it is permitted, then you can show your advertisements against the wall in the dark. You could blow the image up as tall as possible (the image will only be focused up to a certain size]. Of course you won't be able to leave the projector on for extreme long periods of time as the bulb will soon burn out.