Concur with the Home Depot option, their rates for additional time are quite reasonable. One gotcha: Last time I tried to rent one, I had forgotten to bring my proof of insurance, and then realized it wasn't even in the glovebox of my car, whoops! It was my mistake, but it delayed the day's activities while I ran home to get it. At the very least, it'll save you a slog back out to the car.
They don't do reservations, everything is first-come-first-served, so call ahead to make sure one is available. You might be better off renting from a different nearby store, than standing around for hours pretending to be fascinated by floor scrubbers while waiting for one to be returned.
Rear-wheel drive in this weather will be an adventure, though...
-Nate B-