Thanks for the information. Even though the instructions said that you can mount to the metal floor it just didn't look solid enough. I guess if it's working OK for you I'll give it a go. I could always run a piece of angle iron later like BDLuke did if it doesn't feel solid enough.
I had the dealer put the spare tire on the rear bumper. I just couldn't imagine trying to get that tire out from underneath on a dirty busy road in the rain. You do realize that's when Murphy guarantees you'll get a flat?