Jerry,

That sounds like your block heater outlet. As for putting in an outlet for the battery charger, it was easy on my 99. If was a straight shot through the engine bay ceiling from the TV cabinet in the bedroom into the bay directly in front of the engine bay. I, at the time, had an IOTA 24V charger that was not wet environment rating. It worked well in that bay on the sloped floor above the tag tire.