If you make 4" traps, with open back, fully covered in burlap then placing at 4" distance from the wall gives their optimum effectiveness.so 4'' thickness at 4'' from the corner is what you saying? not 16'' from corner like i read? what about the animal question i asked as well? i assume be safe around my cats if the fiber glass is properly wrapped right?
You may want to place then in corners where they have a bigger effect, and in such a placement their distance from the boundary wall is variable, ranging from say, 0" to >10" at their center.
It's safe to have fiberglass if fully covered considering that pets sometimes want to scratch every fabric surface they find. An appropriate elevation to 2-3 feet from the floor could solve the issue.
Also, mineral wool, is a viable alternative to fibreglass. I've found it's much cheaper compared to fibre glass for equivalent densities and just as efficient for sound treatment as fibre glass.