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I am not sure if the transom has a wood core, if it does, you may end up with a rot problem in the future. Get a fiberglass repair book and it will show you how to make an oversized hole, then how to re-glass/epoxy that big hole - once it is cured, then you can drill the smaller hole for mounting - that way the smaller hole is completely sealed and water cannot enter the transom.
If you look up the motor mount supplied by Hutchins in the West Marine cat. you'll see that it is rated for 20 hp. I never have heard of that much hp on the back of a CP-19. Mine is 5 hp.
The entire hull deck and cabin is hand laid fiberglass epoxy impregnated matt. Zero core. What the hull does have on these hard points is some plywood fiberglassed into the area of the bolt holes for holding up ladders, motor mounts, pulpits etc. No worries. When rotted the ply wood can be chopped out and replaced, epoxy ed in and things hung again on it.
To fit my motor to the mount and be able to use the very last notch when pulling the mount up I did have to grind the round away to a flat so the handle would buddy up to the rub rail. Additionally I lowered my motor 2" and moved it back off the mount 2". See pictures.
skip.