I wanted to, but I went portable.
Someone took out tambour doors to the end cap overhead, and built speaker enclosures. I had the same idea, with the addition of a subwoofer built into the dinette frame.
I decided against it ( for now anyway ) ….reasons
#1 It would be a power drain
#2 I mostly just sleep and bathe in my camper
#3 An expensive installed system would get beat up by heat and cold
#4 At most of the events that I go to, there is live music everywhere.
Recorded music is frowned upon, because it interferes with jam sessions
Addressing what you called stereophonic effect. I don't think it would be a pleasant sound. Campers are to small to get much more than a ringing sound. I also think that built in speakers would rattle the cabinets at loud volumes.
I am getting a headache thinking about what you said. ha ha. Now I am probably going to spend weeks, aiming speakers, to see how the curved surfaces treat the sound waves.