Stopped in to the new Auto Zone that opened in our little town for the first time to get some tire cleaner for my daily, and parked next to this OBS Ford. There were no other customers in the store, so I'm assuming it's someone that works there.
One of these should do it. You will need a 16-18 vac transformer to power it up.
Ugh, link is posting as media attachment. Search Amazon for Altronix AL624.
Edir:
Nevermind. Just saw that you're charging off of 12 vdc.
Went Christmas shopping at the "fancy" mall yesterday and saw this in the Tesla showroom. It's goofy looking and the bed side panels are a bit wavy, but it's a lot bigger than I thought.
Interesting, my 89 does the same thing intermittently. I fixed all the grounds and still same. It tends to do it less frequently on dryer days. Acts up more with humidity (not necessarily rain). I will have to check the harness at the tail lights.