Your info says you are in zone 7, so your dahlias are going to be done blooming soon. I would suggest trying to pot one of your smaller plants, bringing it inside during nights to avoid frost and transport it, being sure to fertilize and water in Florida very often. I wouldn't plant it in sandy soil, unless you amend the area around the tubers VERY well, and water often.

You most likely will be able to extend bloom time, depending on how bloomed out your plant already is. Choose one that has just started blooming, as a July bloomer might be disappointing.

For the rest of the plants, I'd dig and divide the tubers, and take them for the ride.

I extended blooms in a plant transplanted into a pot on the porch for a month past frost one year, but the blooms were small, weak and colorless as I couldn't water as much as I should have, and the fall light was too diffused through the porch window. I finally chopped it down, dried it up, and threw it in the basement still in the pot.