That looks like it is concentrating a lot of stress in about 1/5 the area of the original mount. Have you engineered flanges for it to replace the width of the original?
@SailDesign These are rough sketches, just something I uploaded in case I want to start a future thread on the topic. To your point, I would likely integrate the new perpendicular knee into the existing fiberglass structure to take advantage of all the additional laminate already in that area of the hull. It would also give me the option to add a shelf to the bottom to tie all 3 mounts together and to the main bulkheads, but like I said currently just something I was playing around with while working on other projects.