Is there any way to create a transparent view on Android?

Hello there! I am trying to develop an AR app using Unity and Android. My approach consist on an Android view displaying frames captured by camera, and an overlaying Unity view displaying augmented reality objects.

I have successfully sent data between Android and the Unity Player, however, the problem comes when I put the Unity Player view on top of the camera. Since it has a background, the frames are never visible, and therefore the AR effect is not achieved, only the Unity elements are visible.

I know this could be achieved using a GLSurfaceView and setting the instance of UnityPlayer as a renderer before Unity 4.2. I am using 4.5, and I have not found a workaround so I can get the desired effect. Does any of you have an idea to get this working? I would really appreciate if you took the time to write an answer!