Not very easily. Or not in the way you (I think would want to). Florida is not flat. Miami is just around 16 ft above the sea level while Tallahassee is 190 ft. So rising water level would flood the penisula part first rather then closing gap beetwen Gulf and Ocean.
But there is a belt, coming from Spring Hills, Dunnellon to Ocala, Palatka and ending In ...
Here is a projection of Florida with sea level rise.
Maybe your future people avoided this by excavating out the peninsula at about the level of Daytona Beach and moving the fill to Miami to keep it above sea level?