I've seen it done a few years ago. MH at flying J, realized right after he started engine. Had to have 100+ gals of mix drained and then filled with diesel. Local Fire Dept got plenty of fuel for drip torches.
In regards to BFL13, yes the battery disconnect should be on the positive conductor for just that reason so you don't have any 12 volt circuits energized.
According to NEC 551-4(c) bonding voltage converter enclosures, the noncurrent-carrying metal enclosure ... shall be bonded to the frame of the vehicle with a No. 8 AWG copper conductor minimum or equivalent. It further states the grounding conductor...