Before you start drilling holes and putting on hangers, I found if you make a loop of kevlar rope inside some fuel hose, and have that around the mast like the A class, you can adjust its position by clamping it in the end of outhaul car slot. Means no corrosion, or pull outs, and less stress on the boom.
I also used 3 x layers of chopping board bolted together for my boom plug, and hollowed an inside cavity and put a key (a piece of rivet nail) athwart the gooseneck rod. The boom will only come off if I turn it 90 degrees so won't shake loose going downwind when tension is off everything.