All commercial vehicles are required to cross the weigh stations in Florida- no matter how small the vehicle is. Anyone renting a truck for personal use is not required to cross the scales, but the weigh masters suggest that rental trucks go ahead and exit at the weigh stations. The scale masters can't tell whether a rental truck is being used commercially or not, so they may chase down a rental truck that passes by the scale without stopping. Generally, a rental truck that obeys the weigh station speed limit will be directed into the bypass lanes and return to the freeway.
BUT it also states...
All rental trucks and vehicles with trailers are required to pull into the agricultural inspections. Vehicles entering Florida will be prohibited from transporting citrus plants but other types of plants are allowed. Florida will require anyone transporting plants or livestock to fill out forms at the agricultural inspection. Florida will send inspectors to the final destination marked on the forms to inspect produce plants.