Be you but respectful. By writing this you show you are respectful so I think that is covered well.
If it was me, I would simply ask her for her preference and the fact you are willing to alter your appearance illustrates your character well!
Have a great time celebrating your loved ones marriage! Regardless of some hair follicles or not they will embrace such as great personality. Expect the usual peanut gallery stuff but they don't matter so much and I am sure you have thick skin when it comes to those who view things differently than you.
Living free starts with understanding ones own emotions and emotion affects and controls us.