Just get a decent portable Bluetooth speaker!  You can use it inside the RV, outside at campfire, take it to the beach, or anywhere around the yard.  I have the 
Sharkk, but the 
Creative Roar would be even better.  BT or 3.5mm line input.
Once I wanted to replace my TT stereo.  The HU is so un-user friendly and remote rarely works with it.  Speakers suck inside and out.  I was looking at $400 for a decent quality replacement HU and speakers.  I'm so happy with my $20 home DVD player, $1 RCA to 3.5mm cable, and $60 speaker.  Less money spent and way more versatile.