This weatherproof MIL-REM70 wired remote works with select marine receivers, including the JBL-PRV175INF-PRV250JBLPRV275, and INF-PRV315. You can surface-mount or back-mount this remote, depending on your preference, but you'll need to drill a 1-1/2" hole for the wire. 

Product highlights:

https://pdf.crutchfieldonline.com/ImageBank/v20171021163500/Manuals/822/822REM70.PDF