Good work on the SS plate, very clever. I'm not a big fan of self-tappers, I much preferred to use stainless bolts and rawlnuts for rod holders etc. Where I had larger potential loads I would stack a couple of progressivly larger SS washers to distribute the load across a larger area of the hull. 
Hope you enjoy the new ride, and looking forward to some great island hopping stories. If you're interested I'll send you the link of some of my last Hinchinbrook hike photos to whet your whistle. 
 
Ant