Great thoughts. I was curious to know if I could solve the tracing stairs problem; I am have no carpentry experience to speak of but, I teach math so it piqued my interest.
My solution was that if you have a board you know is square on the end, (say a short 6” piece of one of the 2x12’s) what I would do it stand it vertically on the floor next to the board you are tracing in the exact position you want the diagonal board to be in. The short board simply translates the fools up the board at the correct angle at that place. You can do the same thing off the wall for the vertical trace. One you have those lines on your board you can easily copy it to the correct location on the 2x12.
Anyway, thanks for the great read and insight.