Which tool or method should be used to make text on a whiteboard look natural / right?
Your use of pitch and yaw is correct, but it looks like you have just overcompensated a little. Your vanishing point for the lines is too near - that bottom line shows this by angling up too much.
If you correct them by assuming the vanishing point from the top and bottom of whiteboard, you will get a more natural look, and then your text will look more natural.