I'd put an inline fuse tapping off the battery for that, personally.

Well, no, but I've got an added fuse block under the hood wired to a buss bar that's connected to the positive battery cable ...

And you mean the side marker light? Take the headlight bezel off, it's twisted into that. Well, into the turn signal assembly, which is for OEM bolted to the headlight bezel (or "headlight door") assembly.

RwP