An opinion.
Our Hunters are so not ready for a knockdown that speakers can hardly make a difference. Unless you have extensively modified your boat those two 4" holes will not be noticed were you to turtle.I mounted mine in the coaming a little above and forward of the stern seats. I wanted the tunes up where I could enjoy them, not down by my feet. My speakers are marine type, there is no fabric cone that can collapse and let a lot of water through.It is also possible to eliminate any chance of water through the speaker holes. Glass in a heavy bowl shaped fixture behind the new hole. Then seal the small hole for the wire. You can even make the "bowl" with a mold, some cloth, and West System epoxy.