You don’t need a backing plate inside the mast for a cleat. Take it from hundreds of racers. There is a new way to use line on the mast instead of drilling holes, but I haven’t looked into it. I think a Lee Montes video on YouTube covers it but I’m not sure.
You are so wrong.I doubt anyone finds the saga of my upgrades interesting, but I'll continue nonetheless. Here's the new mainsheet bridle.