Spend time making the boot safer, getting a good battery cover, strapped down, not have too many metal objects sliding around, and putting time into making sure the live cable cannot be severed by the sharp edge of the hole it comes into the boot through. Maybe fireproof the boot as well if you like, but I think it's more important to put battery cut off's in, have a fire extinguisher just in case, and ensure the live cable cannot be broken and thus create the sparks that help start the fire.
You could have an extinguisher system installed in the boot that was deployable at the push of an interior button (don't have to open boot and feed fire oxygen) but that's only good if you know the fire is there, which as said, is unlikely
A little offcut of that Samco style blue engine piping would be a perfect tubing for the wires coming in through the boot floor, if the right diameter, as it's very strong and very thick.
Edited by LuckyThe1275, 28 October 2010 - 07:13 PM.