I have seen electrolysis do some pretty incredible things, but being a trunk lid, the anode or steel rod would somehow need to be placed inside the trunk lid to be effective i think. Like cleaning a pipe, it would take the path of least resistance.
The places that do acid dipping are few and far between, would be worth looking into.
I have a similar issue with the trunk on my Barracuda, im going to pry the seam open and take it apart. No acid dipping in my area at all.