A while back I picked up a couple of insulated terminal posts at the local pick-yer-part yard. They came out of mid-80's GM A-cars (Celebrity, 6000, Ciera, etc). One of these days I will get around to installing one of them. Some GM trucks have a similar item, basically a threaded post or two fastened to a plastic base that is held to the fender apron by a couple of sheet-metal screws.
Or something like the first item on this page: http://www.wire-works.com/groundingandcharging.php
Or something like the first item on this page: http://www.wire-works.com/groundingandcharging.php