Yes, this is truly a challenge, (I even somewhat envy you). And it's not something impossible. In that sense, I would agree with the previous comments. Still, a big question remains whether you have decided what forms the basis of your visual work? To some extent, that determines what physical posture you will adopt: sitting in a chair, standing, lying down, what position your hands will be in, and the like. Also, it is important to clarify to what extent your inner and quiet magical work can fit into the atmosphere of the house. Can you say whether your magical work is in some way compatible with your family's faith? Or is it perhaps directed in a completely different direction? Just as it is important that no one notices that you are doing something unusual, it is equally important to isolate yourself from disturbing others. So, you need to have a plan.