Installing a screen

I'm planning on adding a Stewart screen, instead of projecting onto the wall. However, I have a fireplace with a mantle smack where I want to project to, so I have to install the screen such that it is about 10 inches from the wall. Ceiling install is not an option, because of very high ceiling. Has anyone encountered this situation? How did you solve it? The installation needs to be aesthetic too :-).
install the screen on the floor and pull it up. if it won't stay ridgid on its own, get your wife to hold it while you watch. i'm not sure, tho, if you should watch the video material or your wife. guess you have to decide which is more aesthetic.
If you can build the wall out using 2x4's you can do that but the further your screen comes out the further back the projector is going to have to go (depending on the projector of course). Make sure you hit the beams when you screw in the 2x4's so you have a sturdy base. You may want to use a 2x6 as the first board so you can put braces underneath because 10 inches is alot to come off the wall. You have to take sag into consideration. What you might want to do is have a carpenter come in and buil a soffit for you to hide the screen in. Make sure you bring up the problem to him so he knows how to build it. I hope I gave you some ideas. Let me know how it works out.