I am trying to install a porch swing on my front porch and am having trouble finding the main supports that run horizontally. I can find the 2X4's that the ceiling panels are nailed to but can't find the main supports that these 2x4's are connected to. How can I find these supports without cutting into my porch ceiling? What else can I screw my swing into to to be stable enough to hold two people on a swing? Thanks!!!