wow I never did it out of the car, that's ballsy, lol.. Face it up, put it where its serviceable, its gonna be the only part that fails, lol.
When I get to that point on the truck I was thinking about putting in 2 next to each other so I can just plug the other in if it fails on the road, lol (I'm kidding), but keep in mind you will change it at some point...
And I agree passenger side with out a doubt...