I am retrofitting a mount off of a different boat that was made for a larger hole in that boats console. I am have to either drill holes in the existing holes in the sherms mount into my fiberglass in my console which I prefer to not do. Alternatively, I drill new holes in the sherms mount to align to the hole in my console. If I understand you correctly, you utilized the edges of the 90 degree lip in the back plate to caddy corner the hole in the fiberglass console to act as a wedge prevent movement .Thank you for feedback; it is appreciated.