I had a shop build a u shaped stainless gusset bracket to fit inside the flange with the existing holes in the port side of the roller stay pin. Then I bolted the whole works together, and immediately found the measurements were too tight and the pole touched the furler drum. So I simply moved the whole works so one side of the gusset was outside the mount. The kite is about 20% bigger than anybody would recommend, and is intended for use in the windy season here (that's where we spend days looking for the wind) but seriously, is limited to 10kts. With the home crafted top down assembly, it has so far worked like a charm.
I have heard many bad things about using the locker hatch as a mounting place, and I used pretty big backing plates, but my experience has been that there is almost no load back there at all, and what is there is lateral. Any vertical load would be just that. The kite pulls up on the pole, and the back end of the pole is pushed down.
Just like anything, you need to pay attention to the intended use, and set realistic limits on use. I would never fly this kite in 20kts, and the premise of "protect the boat" implies that if the limits are not respected, stuff will break.
