No space is safe anymore, not even outer space. Apart from the light pollution that many urban cities around the world are emitting, a Russian startup called StartRocket had said that they want to launch space billboards. As if we don't have enough ads invading our everyday lives, now this would even prevent us from seeing the stars at night.
(Image credit: StartRocket via Futurism)
I don't think it would be difficult to make a cubesat (or smaller) with a deployed mylar or kapton reflector, and most of the mass being used for fuel and engine for station keeping. It would probably be a question of just finding an appropriate launch to get enough spare room, and to find someone to pay for an ad that is only visible for a few minutes each night. Cubesats can cost as low as $10k each to launch.
I hate the idea but something tells me these guys haven't thought this one through enough.