I'm writing WinForms / Xna app and I need some way to abstract away interaction with the GraphicsDevice in my Controller / Model code.

I've created an interface IGraphicsService. I'll use that to abstract away things like loading textures. What I can't figure out though is what to do when I need to return some kind of Texture information. Should I create a class that wraps Texture2D? I'm worried this will incur unnecessary overhead. I would like to be able to create some kind of MockTexture2D in the long run. 

This is all so that I can make my app more testable. I'm not so much worried about speed but it would be nice if there was some solution that won't incur to much overhead as eventually I want to use this to make my games more testable. Any suggestions?