Good sound marine stereo system for a small catamaran.

[Stellar1970Cat]

I have this sailing cat which is my home too.
I used to install car stereos as a radio technician a while back.
There is not much space for speakers inside and outside I have water proof speakers which came with the boat. So nothing fancy but I replace them in due course to satisfy my ears which are used to studio quality sound but my wallet is not thick enough for it so I am looking for decent sounding compromise.
As a head unit I am now using a Sony CDX-GT50UI. I had very similar Sony head unit on my Sprinter van 10 years ago and the sound quality with DIY 3-way component speakers was great.
So now I just need to find great speakers for the little space I have available.
I could use a subwoofer to get better bass.
I was thinking of buying second hand Bose speakers and 12V subwoofer?l
Any recommendations?
Additionally I want to use the Sony IR remote from the helm.
The head unit is installed inside the cabin at the central entertainment unit so walking inside to change volume or change channels etc is not practical.
I was thinking of using a fibre optic cable to use the remote remotely? Or getting another remote and making it wired IR remote by removing the IR LED from remote and adding couple meters of twin lead cable in between?
Or using IR extender?