As for positioning and scaling the tracking space, we generally let the visible area of the Looking Glass correspond to about a foot of physical height, starting at about 4 inches from the LEAP (the minimum for solid tracking). A more subtle consideration is the angle relative to the Looking Glass, which sits at a 61 degree angle to the table. Picture it this way: when moving your meat hands around on a plane parallel to your table, do you want the 3D hands to look like they're moving parallel to the table as well, or parallel to the bottom of the Looking Glass block? A conceptually accurate -29 degree offset always feels like too much for some reason, so I usually set it to somewhere in between, -15 degrees or so.