Besides the OP's mention of the stock being 8/4 popular (how many of us have planes to work two pieces held together of this width?) this method always sounds a bit off to me.
Yes, side to side angular deviations are canceled.
Any vertical deviations are multiplied.
On Shooting Boards
Here is a thread, over a decade old, that includes one long edge shooting board > https://sawmillcreek.org/showthread.php?92355
A lot of old images in woodworking publications show a plane being used with a bench hook for shooting work. The bench top is the ramp.
jtk