You can always "Split" the DC to feed multiple devices up to the max load rating of the outlet.. I mean from where I sit I can see a Rig-Runner 40-12.. This is a distribution panel with 1 inlet and 11 outlets as I recall Anderson power poles, fused at 40 amps (your outlet is closer to 10 max 5 to be safe).
As much as I kind of like a quality blue tooth pair, the analog-digital - analog conversion takes time, You won't like that, Thus FM radio types are best (no or very little delay).
One thing that might work.. your dash radio.. The link I will edit in explains how
Several options, Pick one of the FM onesIf it loads.. I actually have one of these, works good, rechargable via USB cord.
Home was where I park it. but alas the.
2005 Damon Intruder 377 Alas declared a total loss
after a semi "nicked" it. Still have the radios
Kenwood TS-2000, ICOM ID-5100, ID-51A+2, ID-880 REF030C most times