One of the best systems available for playing music in various locations is made by Sonos.
But you will require a wifi network and router in your coach for it to work. They have models that have built in amps to power your speakers, versions that have speakers built in, or versions that require separate amps and speakers.
I utilize 2 units in my coach. One for outside speakers that I hang on the side of the coach and one for the inside system. I also have a hard drive with 20,000 lossless songs in my music library. They are perfect for at home as well. Capable of playing music in 32 different locations in your home. Google Sonos. It is not the cheapest way to go but it is a proven system that allows you to control it with an app on your phone. It will even play music stored on your phone.
2009 Newmar Ventana 3942
2010 Pace Shadow 18ft
2010 KTM 450 XCW six days
2010 Can Am Outlander 650 XT
2014 Can Am Outlander 500
2007 Yamaha YZ250F
1989 Douglas Skater 21' Twin 2.5s