I have a 10 in helix mounted via a horizontal Kong mount to the side of my Z21 console. The last trny we had heavy wind blown chop at bast off and I suffered a mount failure. It was not the Kong mount but rather the fiberglass. It was mounted by "pro" installers, but it was not a "pro" job. The Kong mount has holes for 6 bolts, only 3 were used in a triangle pattern. The installers used fender washers but one was 1/2 the size of the other 2 and it was the top of the triangle. Guess which one pulled/cracked the fiberglass. I did not discover this until it broke. I had the fiberglass repaired. Built a backing plate out of 1/16" aluminum plate and shaped it so that it followed to roll of the upper console corner. I used all 6 bolts and additionally, used 1.5 " fender washers and shaped them as needed to the roll of the console. If this fails, it will have to pull the side of my console off.
I have seen many boats done this way. Check the backing used to make sure it is sturdy enough to handle the load.