the thing is both battery grounds need to pass thru the RVC and then to ground, so from battery-to-RVC sensor-to ground this is so the bcm can see what the load is correctly, with the 2nd battery being way over on the other side of the engine compartment you need a long ground about 80" to join them together, using a distribution block would be fine but it would need to not be grounded previous to the RVC sensor. I'm just trying to simplify it with a different top post adapter if that wont work out then I'll try something else