Thanks for the comments guys!
I'm new to the Focus, so can you tell me exactly where the fuel cut-off switch is located and how it is operated? I've heard that this is a feature on these cars, but I just don't know anything else about it.
There is a good inch or maybe two of space between the floor and the top of the tank. The things is, as pointed out in the original post, there are all kinds of lines running underneath. If you are not extremely careful, something could get nicked!
With the plate bolted back in place, and gorilla tape (thanks previous poster) over the cuts, and with the interior carpeting and the seat back in place over the plate, you really cannot hear much additional road noise.