Changing the angle of the boot board (Zeppa) and sole canting accomplish two different things. Changing the boot board changes varus and valgus of the foot and changing the boot sole angle changes where the edges engage in relation to knee position over the ski. These are two different areas and I believe the former affects balance and the latter affects edge engagement.
Your boots are TOOLS NOT JEWELS! Why be afraid to plane them? Why be afraid to cut up your liner, or grind the shell? What is the down side of having a tool that works for YOU. If you are worried about resale value of your prized boot......get over that right now!