Kane for your system i would have to say change amps on the cabins/sub. Get the 700.5 or a amp comparable to that. Just doing that you will increase the sound in the boat by a huge amount. This will also play back to when your surfing because you will hear the sub a bit more while surfing and it will all sound better.

As for the rest looks great for your end goal.

I can say when i did my first stereo upgrade, i took the same two Kickers out and put in the 700.5 and the boat really came alive and rocked really well.