I'm not really savvy on wiring. I have replaced and tested GFI outlets in my house though, so I figure I should be able to do a serviceable job. I have a 2012 Coachmen Clipper 108 sport, and I'd like to hook up a 12 V outlet inside, mostly for charging cell phones, although I might also use it for a few other 12V devices. How should I do this? Thank You.