G'day Ross,
Your spare tire should sit on a mounting plate. Then there is another circular plate that bolts over that to secure it. It's kind of hard to describe. If you can't figure it out, take a photo of your situation and post it. I removed all the "guts" from my tailgate since I have a full size spare that doesn't fit anyway, otherwise I would take some pics for you.
Hope you are well away from that nasty conflagration down there.
Bart