While mounting a hardwired stereo presents an issue of the where to put the head unit due to the space requirements, the space for the speakers is also an issue as well as being able to run the needed wires to all. So that needs to be part of the equation.
Since not familiar with your boat, I checked out a couple of walkthrough videos folks have posted but they did not have stereos. Nice boat but wow, where to put a stereo? Perhaps you already did this as well > I checked out a few “for sale” ones and did not see any pics with a stereo. But not to despair, I think there are multiple possible solutions.
If you are playing tunes from your iPhone a portable (and rechargeable) Bluetooth speaker is an option. Something like this
link. It’s cheap enough that if goes overboard / gets lost its not that big of a deal.
Next step up would be to hard mount a couple of Bluetooth speakers, no head unit required. While these (
link) are meant for mounting on a wakeboard tower, etc. it gives you an idea of possibilities. They
do require hardwiring and this setup requires one speaker to be connected to the other, so getting a wire across your boat needs to be considered.
For a full head unit (AM, FM, Bluetooth, weather band) an incredibly small unit like this unit (
link) requires only a cutout for the head unit of 3” diameter. Can tuck that baby anywhere! But again, will need to hard wire and run wires to both speakers.
My suggestion is to explore where and how you can run wires to determine both feasibility and degree of difficulty and base your decision on that. If nothing else that first choice of a portable BT speaker gets you going with some tunes at an affordable price point while you get comfortable with your new boat and have a better feel of what you would be ultimately comfortable with.
And please post your thoughts and decision for others to benefit from. Thanks!