Go to the bathroom in a city before you get to SOTB (bathrooms are nasty). Stay in SOTB long enough to say you were there and continue your journey. Florence is about 40 minutes after that and is a good place to stay for a night if that is what you are looking for.
There was another thread somewhere that talked about SOTB. Do a search and get the responses.
ETA....Plan on a meal in Florence as well....or a town before SOTB.