One tire with an off size will be less of a a problem on the highway than the typical passenger car "donut" spare. I personally wouldn't hesitate to drive on the highway with three 33's and a 32, but on the other hand I wouldn't be screaming along at 90mph around curves. Use a little common sense.
Hey everyone thanks a lot. This is great news. As far as I can tell (i.e., from my perspective) this will save weight, ground clearance & $. And yes I would drive very conservativly w/ the smaller spare & plan on reparing or replacing the damaged tire ASAP.
The biggest issue with the stock spare (IMO) is that it's a highway tread tire. If you get a flat way back in the woods (or several miles down a loose sandy beach) remember that you've lost a significant amount of traction on one tire. You'll still have 4WD, but chances of getting stuck will go up. I recommend replacing the rubber (sell the old spare to a used tire place or on Craigslist), but nothing wrong the with the stock wheel.