Not sure about how they charge with a MH+toad, but I know that for the car, Sunpass saves $.25 each toll. There should be a site somewhere that will tell you how many toll booths you'll go through, so you can determine if it's "worth it" or not. I know that in a lot of the toll booths, the Sunpass lane is totally separate and allows you to go through at maximum speed, so there's a time savings as well. A lot of the booths operating on Alligator Alley and in the Miami area are electronic, "no stop". They bill you based on your license plate. The Sunpass still saves you the quarter down there as well.
Eric, Melanie and little Maddie, 15lbs of Malti-poo energy
1984 Southwind Eagle I (she might be old but she's capable)