A:AnswerI dont know about clearance but there is no back part or protection from the back. They are open to the ceiling once mounted. I never thought about making a box for them up in attic like you can for a car woofers.
A:AnswerActually a 2x4 stud is 3.5" and residential drywall on walls is 1/2" and maybe 5/8" sometimes, so that is only 4" - 4 1/8"total. I am also concerned with buying these for the location I need them as it is a 2x4 stud wall.