I would definetly look into getting some kind of rack for that distance. You may also look to store essentials at your work so you don't carry to much when you do commute. It doesn't sound like the distance will be a problem since you average over 250 miles in the florida heat and humidity. Will you try and commute everyday, or 2-3 times a week plus try to get your 250 miles in?

I also suggest you get handy with a wrench if you are not already. It also sounds like you have multiple modes of transportation available to you (bus/car). At first you may want to ride half the distance then use some other means of transportation to finish off.