Yes, you should be able to get insurance for a car you buy and register in Florida if you obtain a Florida driver's license. According to the FL Department of Highway Safety and Motor Vehicles, Canadian citizens are non-immigrants and are allowed to stay in the US without obtaining INS documentation.
Canadians without INS documents must provide proof of Canadian citizenship to be issued a Florida driver license by presenting 2 of the following documents: Canadian passport, Canadian driver license, Original or certified Canadian birth certificate, Canadian Naturalization certificate.
Florida requires any part-time or seasonal resident living in FL for 90 days or more during the year to obtain a Florida personal injury (PIP) and property damage liability (PDL) auto insurance on their vehicle.
For the months that you are not in Florida you must continue to maintain insurance on your vehicle or surrender your Florida tag and registration at the nearest driver license or tag office. If you choose to do this, when you next return to Florida you can register the vehicle after you have obtained proof of FL insurance once again. Since it sounds as if you plan to leave your vehicle in Florida for the full year, then you will want to continue insurance on it for that whole time.
To get a quote for Florida car insurance, click here.