Kim I don't like that method, because with the battery killed, YOU STILL HAVE a fairly large "welding cable" (sparking and arcing) that is live from one end to' to other. Crackedback takes one approach, mine is to use a "4 post" switch, which nowadays are VERY available. What you do is, if you have EFI, but the small posts in series with your pump relay. If you run a carb, use those terminals to kill a relay feeding the ignition. What that switch is off, wired that way, ALL power is "in the trunk."
On a side note..........you need a MUCH larger charging wire for a "one wire" system. Perhaps at least no6 and better no4
