When it comes to electrically powered objects, remember Occam's Razor: The simplest reason is usually the answer. Don't go tearing out walls just yet....
So my '88 doesn't come with a music radio, but I assume it's in the top half? I would check your fuses first, then look at common fail points. The coil cord, the converter box, and the inside of the battery box. My trailer had a really weird setup where the top half wiring ran into a junction block in the battery box, causing a weak point.
Fixit Wrenches and Lizard (mostly Fixit)
Chris and Liz
1988 HiLo Funmaker 2088L, an oldie and goody!
2001 Ford F-250 Pickup w/ 7.3 Diesel (best engine)
Proud Campers, ES, SAR, and Firefighter Rehab