Logic Question with position and parenting

Hello, I'm trying to move a child object of a "room" to be on one of the four walls of the room. The problem I'm having seems to be with the fact that the parent, or room, is scaled to fit a specific space, so for example, 12x6x8 (x,y,z), so when I tried to move the child based on the parent's size/extents with localPosition, it moves the child very far off. If I manually move it, values like .2 come out to be half the room's size when moving the child, so if I move the child .2 it will be on the wall. I'm having a hard time figuring out how I can move the child object precisely to the parent's walls when the scale of the room is messing with the localPosition values of the child. Any tips on this? Thank you for reading!