Anyone installed extra d-rings in their toy hauler?

If I remember correctly, I think I was careful with the hole saw to estimate how deep I needed to go to get through the plywood layer, then I stopped when I got into the styrofoam. I carefully dug out the styrofoam just enough to get the depth I needed for the new anchor point. I'm not sure what's below the styrofoam, but what I did before cutting any holes was to unscrew and disassemble one of the existing d-ring pockets. I kind of reverse engineered what was there to match it as closely as possible.