I am going to attach a piece of plywood across 3 studs and then attach the mount to the plywood, as described in the answer to Studs not in right place for mounting TV. Can I use 2x4s to extend them?.
However, my wall slants inwards 8 degrees ("inwards" meaning that the bottom of the wall is further out than the top). How should I handle this so that the mount is ultimately vertical? One thought I had was to have a 2x4 cut to the right dimensions with one side having an 8 degree angle to match the wall. I'd then place this on the bottom of where the mount will go, ultimately leaving me with studs > 2x4 > plywood > mount on the bottom, and studs > plywood > mount on the top.
Is this the right approach?