I suppose that would work given a good solid, clean connection to bare steel.

I ran cables from my dual batteries up though a pair of quick disconnects (power and ground cables) and then tied the 2 ground cable to the frame up near the front shock mounts. This way I could still keep the batteries separate at the connectors so I could put them in series if needed, for example for welding.

Also, I kept all the heavy frame ground points at the same location, so the original frame ground, my two new ones and the winch all come back to one point to minimize having 100s of amps of current flowing though parts of the frame.