[villagetinker]

You will need to add insulation to the ceiling area of the garage, and this maybe complicated if you have attic storage. You will probably want (need) to insulate the garage door. IMHO, I would definitely go with a minisplit. Most if not all of the ones I looked at required 240volts at 15 to 25 amps which typically require a permit and licensed electrician. I know there will be several who will disagree and state that you can DIY but I believe there are limits on the type of DIY electrical work. Also, I think FL requires a license for the refringent lines. As for the portable AC unit, you cannot use a window AC unit, you may get away with a window exhaust type unit with the large flex exhaust hose. Be sure to look at the customer reviews on these, and also figure on where and how you will handle the drain line.