I did these mods to the transom two years ago not had a problem with the water coming over the top since,
Transom mods aerotec 380, Pictures
Some pictures of the transom height mods
I've done to the areotec. Two heights for two different engines, 25mm for the mercury 15hp and 50mm for the Johnson 30hp. With the engine sat in-between the plate it can only go in one place so centralizes the motor every time. Have used 8 of the 9 same screw holes in the transom so its not laced with holes.
Just need to got 2 bolts to finish it off.
I've since dropped the height down to 40mm as now using Tohatsu 25.
This is from a post 2 years ago but don't know how to link it in.