The best "grounding" system is to NOT rely on "grounding", which uses the powertrain, body, & frame metal as the electrical power return. It was a cost-reduction concept in early electrical power systems (utility power distribution used the actual dirt of the ground, which is where the term comes from), but with the cost of quality Copper wire today, and with the added loads & low-current signals of modern electronics, grounding is now only done for radio shielding (RFI).
Look at how the original Explorer harness return (negative, "ground") wiring was built, and mimic it. Personally, I prefer to USE the modern donor wiring harness, instead of something aftermarket. Ideally, you'd have a heavy Copper wire running through the vehicle (no bigger than the original Explorer negative battery cable), with progressively-smaller branches coming off it going to each electrical device. Nothing would rely on any connection to old steel for electrical power - Copper all the way to & from the battery terminals. A few of those small branches would hit the body & frame just to prevent RFI, but never to carry any significant current. Only the block needs a heavy ground for the starter, alternator, & its truly-grounded devices, like a few of the sensors.
