The original Van's battery holder was designed to accommodate lead-acid and gel cells weighing up to 25 pounds. I committed to Lithium Iron Phosphate (EarthX) weighing less than 4 pounds, Such a heavy duty battery box was not needed.
I disassembled the battery box to find that my partner had drilled very large holes about 75% over-sized. These needed to be beefed up. Conveniently, I found that the hole pattern was just right to hold the two contactors.
I used a small section of angle on the baggage side of the firewall to add some rigidity and to create a gas barrier to the dirty side of the firewall.
I used a couple of countersunk pop-rivets to hold the assembly together. Once the bolts are tightened, we should have a strong, safe firewall.