Our family room came wired for surround sound that we won't use (see pic). I know I can buy metal plates that screw into the boxes after removing the existing covers. As there's only speaker wires and no electrical, I'm comfortable doing this.
My question is that since we intend to put wallpaper on this particular section of the wall where those boxes are, I need to spackle over the wall plates I install. That is, I want to completely hide the speaker boxes such that when wallpaper is applied it will completely cover where the boxes were. Is there a way to do this to ensure the spackle won't crack and the wallpaper won't wrinkle over time?