Just make sure you bring plenty of coins! I forget which particular exit it was but it was the last one we got off at before reaching Windsor Hills. Anyway, at that exit, the only options to pay were Florida SunPass or exact change... coins only no toll operator. I believe it was .75 cents. All we had in coins was .60 cents so we just threw that in. That was the only toll booth we encountered that did not have a toll operator.
I called our car rental company, Alamo, and they said the toll authority will will send them (Alamo) a notice and a bill and Alamo would then bill us for it. The person I spoke to also said that Alamo would typically also assess a "toll violation" service fee but they said they would waive that penalty since I called them in advance and explained the situation.
EDIT: I will add that it was late at night, around 11pm. Maybe they have operators there during earlier times in the day. Anyway, just be sure you have plenty of coins and you'll be good.