The best preventative maintenance you can do on a vinyl roof is to peel it off and toss it in the trash. Especially in Miami.
Even 100% garaged there's probably enough moisture in the air to rot your roof, if it's not inside forget about it. You might as well start looking for a new roof skin right now. If a vinyl top can rot out a roof skin here in California away from the coast it sure as hell will in Florida. I have one car that needs an entire roof skin because of a vinyl top, it was never within a 100 miles of the coast according to the previous owners. It did sit outside, and that's all it takes. My Challenger needs not only the roof skin but some sections of the hard top structure replaced because of a vinyl top. It went from Utah to Florida at some point, but I'd be willing to bet that the roof rot is from Florida and the salt air/humidity. Vinyl traps moisture, moisture causes rust. It's not likely they'll reproduce roof skins for an A-body sedan any time soon.
If you've got it garaged somewhere climate controlled do whatever you like. If it's going to be outside under a cover, you should think about pulling it and painting the roof. I'll wait for all the red X's, vinyl tops were just a factory gimmick to cover the quarter seams with less bodywork.
