by coincidence, I'm currently playing with this, but sometimes you just have to pay the price.... to achieve everything, it comes at a price
https://www.youtube.com/watch?v=jXFvrkDl7owUnfortunately, I was wearing "hatcam" and forgot to tilt my head down!
mrrcsound use actual recordings of the real thing, this boat currently sounds "tinny" on the stand, as the transducers sound better when the boat is in the water, its more of an experiment at the moment
if you want cheap, just use a Bluetooth speaker that can take an sd card, and download your own tracks, but it wont be proportional.