I have successfully replaced two out of the three wash basin faucets in my house so far, but this one has me stumped:

As you can see from the picture, it's a pretty run-of-the-mill pedestal wash basin. However, what this picture doesn't quite-so-adequately convey is how little clearance there is behind the pedestal to get a wrench in to drop the drain pipe:

I'm hoping someone has some suggestions on how I can get a vise grip or an adjustable wrench behind this area? The clearance is rather small and I don't think they make adjustable wrenches small enough but with big enough mouths to properly twist a trap nut.