I understood your point, and my point is there are other ways to accomplish that without touching your boot board. For example we have added some wedges to the boot board on my current boot, on my previous boot it was a varus wedge. Lots of easy ways to adjust foot position in the boot that are easily reversed and that do not create more volume. Grinding the boot board does create more volume. If you look at all the world cup customization that @otto showed us, they were clearly adding material to the boot board to modify the foot position in the boot.Once again, you're not grinding the bootboard to create space, you're doing so to better match your foot postition to the contours of the shell. Please take the time to actually read what I write if you're going to provide commentary back.
Not saying it is not possible to accomplish what you describe by grinding a footbed, just saying that there are easier ways to accomplish that where you have more control and you do not create more volume.